Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Light and electron microscopic autoradiographic investigation of the septo-dentate pathway in rat brain Rose, Ann Marie 1976

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1976_A6_7 R68.pdf [ 5.1MB ]
Metadata
JSON: 831-1.0093708.json
JSON-LD: 831-1.0093708-ld.json
RDF/XML (Pretty): 831-1.0093708-rdf.xml
RDF/JSON: 831-1.0093708-rdf.json
Turtle: 831-1.0093708-turtle.txt
N-Triples: 831-1.0093708-rdf-ntriples.txt
Original Record: 831-1.0093708-source.json
Full Text
831-1.0093708-fulltext.txt
Citation
831-1.0093708.ris

Full Text

LIGHT AND ELECTRON MICROSCOPIC AUTORADIOGRAPHIC INVESTIGATION OF THE SEPTO-DENTATE PATHWAY IN RAT BRAIN by ANN MARIE ROSE B.A., U n i v e r s i t y of Saskatchewan, 1970 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES INSTITUTE OF NEUROLOGICAL SCIENCES DEPARTMENT OF PSYCHIATRY SCHOOL OF MEDICINE  we a c c e p t t h i s t h e s i s as conforming to the required  standard  THE UNIVERSITY OF BRITISH COLUMBIA June, 1976 (c)  Ann"Marie Rose, 1976  In p r e s e n t i n g t h i s  thesis  in p a r t i a l  fulfilment of  an advanced degree at the U n i v e r s i t y of B r i t i s h the I  Library shall  make i t  freely available  f u r t h e r agree t h a t p e r m i s s i o n  for  Columbia,  I agree  r e f e r e n c e and  f o r e x t e n s i v e copying o f  this  that  study. thesis  s c h o l a r l y purposes may be granted by the Head of my Department or  by h i s of  for  the requirements f o r  this  written  representatives. thesis  It  is understood that  f o r f i n a n c i a l gain shall  permission.  Department of The  University of B r i t i s h  2075 W e s b r o o k P l a c e V a n c o u v e r , Canada V6T 1W5  Date  Columbia  copying or p u b l i c a t i o n  not be allowed without my  ABSTRACT  This tween two gyrus by  s t u d y was existing  undertaken  s t u d i e s r e g a r d i n g the  where t h e s e p t a l  injecting  to r e s o l v e the  fibers  radioact ively  layer  terminate.  labelled  cell  b o d i e s and  heavy  t r a n s p o r t e d to the nerve  in the subgranular  labelling support  was  may  septal  seen  showed l a b e l l i n g  layer.  The  terminals i n the subgranular  described.  onto  d e n d r i t e s and  They  resembled  cholinergic  r e g i o n s of t h e b r a i n . evidence  that  gyrus, These but  findings  indicate  the  molecular of  zone o f t h e d e n t a t e  round  the gyrus  synapses vesicles.  terminals described i n other  These f i n d i n g s agree  the septo-dentate  the  whereas  ultrastructure  contained clear  nerve  by  Auto-  T h e s e t e r m i n a l s formed a s y m m e t r i c a l s p i n e s , and  me-  moderately  Mosko, e t a l . , (1973) i n t h e  have been a r t e f a c t u a l .  was  protein  was  zone of t h e d e n t a t e  i n the molecular  by  dentate  accomplished  terminals.  t h e work o f Raisman e t a l . , (1965),  degeneration layer  scant  be-  amino a c i d s i n t o t h e  septum where t h e y were i n c o r p o r a t e d i n t o  counts  i n the  T h i s was  dial  radiographic grain  conflict  pathway  with  accumulating  i s cholinergic.  iii. TABLE OF CONTENTS  Page No.  TJNTRODUCT ION I.  1  Anatomy of t h e hippocampal  region  4  A. C y t o a r c h i t e c t u r a l arrangement  4  B. A f f e r e n t C o n n e c t i o n s t o t h e D e n t a t e Gyrus  6  C. I n t r i n s i c C o n n e c t i o n s of t h e D e n t a t e Gyrus  8  D. E f f e r e n t C o n n e c t i o n s from t h e Dentate Gyrus  9  I I . S y n a p t i c O r g a n i z a t i o n of t h e D e n t a t e Gyrus ....  12  A. Laminar Arrangement  12  B. U l t r a s t r u c t u r e of S y n a p t i c T e r m i n a l s  13  C. S y n a p t i c A c t i v i t y  15  i n the D e n t a t e Gyrus ...  I I I . The S e p t o - d e n t a t e pathway  17  A. The Septum  17  B. C h o l i n e r g i c n a t u r e of t h e S e p t o - d e n t a t e Pathway C. I n v e s t i g a t i o n of the S e p t a l T e r m i n a l s i n t h e Dentate Gyrus METHODS  IB 19 21  I.  AxDnal T r a n s p o r t t o Hippocampal  Region  II.  L i g h t M i c r o s c o p i c A u t o r a d i o g r a p h y of Septal Terminals  I I I . E l e c t r o n M i c r o s c o p i c A u t o r a d i o g r a p h y of Septal Terminals  23 26 28  iv. Page No. RESULTS  30  I.  Axonal T r a n s p o r t t o Hippocampal Region  31  II.  D i s t r i b u t i o n of L a b e l i n the Dentate Gyrus ...  34  I I I . U l t r a s t r u c t u r e of the S e p t a l T e r m i n a l s ........  36  DISCUSSION  41  BIBLIOGRAPHY  48  PLATES  56  L I S T OF TABLES Page TABLE  I  Time Course  of a x o n a l l y t r a n s p o r t e d  labelled proteins after injection 3 of H - l e u c i n e i n t o m e d i a l septum TABLE  II  Distribution  No.  of s i l v e r  32  grains in  3 dentate gyrus a f t e r injection TABLE  III  into  H-leucine  m e d i a l septum  Distribution  of s i l v e r  the  of t h e d e n t a t e  synapses  gyrus  39  grains in  40  vi.  LIST OF FIGURES AND ILLUSTRATIONS Page No. FIGURE l a  H o r i z o n t a l s e c t i o n of hippocampal region  10  FIGURE l b  The l a y e r s of t h e D e n t a t e Gyrus  10  FIGURE I c  C i r c u i t r y of t h e Dentate Gyrus  11  FIGURE 2a  H o r i z o n t a l s e c t i o n through i n j e c t i o n site ....... Transported s i l v e r grains i n fimbria  57 57  D i s t r i b u t i o n of s i l v e r g r a i n s i n the d e n t a t e gyrus  57  H i s t o g r a m of g r a i n counts i n d e n t a t e gyrus and c o n t r o l a r e a s  58  Comparison of l a b e l l i n g i n d e n t a t e gyrus and e n t o r h i n a l c o r t e x  59  E l e c t r o n micrograph of n e u r o p i l e of d e n t a t e gyrus showing l a b e l l e d synapse "en passage".  59  Comparison of l a b e l l e d synapses i n dentate gyrus  60  FIGURE 2b FIGURE 2c FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6  ACKNOWLEDGEMENT I would l i k e t o thank my S u p e r v i s o r , C h r i s F i b i g e r , f o r his  support and c a r e f u l r e s e a r c h g u i d a n c e ;  Toshi H a t t o r i f o r  h i s p a t i e n t a d v i c e , and J i m M i l l e r f o r h i s c r i t i c a l d i s c u s s i o n . I am g r a t e f u l t o t h e e x c e l l e n t comments and encouragement of V i c Bourne, Joanne S u s u k i , S t e l l a Atmadja, Raja Rosenbluth,  and L a s z l o V e t o .  A s p e c i a l thanks t o W. Maxwell Cowan f o r h i s i n t e r e s t and  suggestions.  Frontisp iece Pyramidal c e l l s i n area c e l l bodies and by dense  parallel  neuropil.  CA1 of r a t hippocampus.  d e n d r i t i c trunks can be seen  Pyramidal surrounded  - 1  The types  identification  and t h e i r problem  central  nervous system.  i n t h e study  t h e neuron w i l l  potential  of synapses of v a r i o u s f u n c t i o n a l  l o c a t i o n on t h e n e r v e c e l l s  portant  on  -  of s y n a p t i c a c t i v i t i e s  if  i t occurs  i t occurs  synapse  i n t h e e f f e c t o r neuron. have a g r e a t e r  branch.  b e c a u s e t h e a c t i o n p o t e n t i a l g e n e r a t e d by a c e l l (Katz,  1966).  In g e n e r a l ,  A  effect, i f  a t t h e membrane o f t h e c e l l  a t t h e membrane o f a d i s t a l  the axon h i l l o c k  i n the  i n f l u e n c e t h e amount o f c h a n g e i n membrane  t h a t c a n be p r o d u c e d  example,  an im-  The p o s i t i o n of t h e incoming  c h a n g e i n membrane p o t e n t i a l w i l l for  represents  body  than  This i s arises in  electrical in-  formation  at the d e n d r i t i c extremes spreads p a s s i v e l y t o t h e  cell  ( E c c l e s , 1964).  body  This  o f t h e s i g n a l and a d e l a y r e l a t i o n s h i p of s y n a p t i c to understanding The  i n time.  dentate  pathways t o t h i s course  Blackstad, al.,  gyrus,  a s an a r e a  part  o f t h e b r a i n been d e s c r i b e d  and t h e i r  site  structure.  of t e r m i n a t i o n  afferent  with  regard  ( C a j a l , 1911;  e t a l . , 1970; R a i s m a n , e t  i s a l a y e r e d arrangement Knowledge o f t h i s  ment makes i t p o s s i b l e t o s t u d y  region,  such problems f o r  have t h e i m p o r t a n t  1956, 1958; B l a c k s t a d ,  to t h i s  fundamental  of t h e hippocampal  to deal with  Not only  1965); but a l s o t h e r e  inputs  i s therefore  of t h e o r g a n i z a t i o n of t h e b r a i n .  following reasons.  to t h e i r  This structure-function  organization  o f f e r s a unique opportunity the  i n v o l v e s a l o s s of s t r e n g t h  inputs  layered  to restricted  of these arrangeidentified  - 2 p a r t s of the granule c e l l , gyrus  the major c e l l  (Lorento de N6, 1934).  type of the dentate  An important and w e l l d e s c r i b e d  input t o t h e h i l u s of the dentate gyrus i s from the medial septal nuclei  (Crosby, 1917/  ^  "  ; Andersen,  1961: Shute & Lewis, 1963: Raisman et a l . , 1965).  et a l . ,  The septum  makes connections with both the hippocampus and t h e dentate gyrus  (Raisman, 1965); the dentate gyrus, i n t u r n , c o n t a c t s  the hippocampal  cells  ( C a j a l , 1911).  Although t h i s p l a c e s t h e  dentate gyrus i n a prime p o s i t i o n t o punctuate the s e p t a l input to  the hippocampus, the f u n c t i o n a l importance  of t h i s arrange-  ment i s not understood. The anatomical p o s i t i o n of the hippocampal i t a key s t r u c t u r e of the l i m b i c system.  r e g i o n makes  Connections t o t h e  hypothalamus through the septum i n d i c a t e a c l o s e i n v o l v e ment i n such f u n c t i o n s a s endocrine c o n t r o l and t h e e x p r e s s i o n of  emotional s t a t e s  (Shepherd,  1974).  S e v e r a l sensory  inputs,  v i s u a l , a u d i t o r y , and somatic t r a v e l t o the hippocampus (Shepherd,  1974) and connections through the septum have been  implicated  i n p h y s i o l o g i c a l a r o u s a l (Green &  Arduini,  1954).  As w e l l , t h e hippocampus probably p l a y s a r o l e i n memory and learning  (Shepherd,  1974).  How i t does so i s undoubtedly r e -  l a t e d to the s t r u c t u r e - f u n c t i o n r e l a t i o n s h i p s of the s y n a p t i c o r g a n i z a t i o n of t h e hippocampus and dentate g y r u s . Although the septo-dentate pathway has been e x t e n s i v e l y studied  (Crosby, 1917; D a i t z & Powell, 1954; Raisman, 1966;  Shute & Lewis, 1961; Andersen, there exist  1961-/; Mosko, et a l . ,  some u n r e s o l v e d q u e s t i o n s about  1973),  i t s exact mode Df  - 3 termination (Raisman, et a l . , 1965:  Mosko, et a l . , 1973).  This thesis i s directed tovjards c l a r i f y i n g the precise d i s t r i b u t i o n of septal nerve terminals in the dentate gyrus and describing their u l t r a s t r u c t u r a l  characteristics.  - 4 -  I.  of  Anatomy o f t h e h i p p o c a m p a l A.  Cytoarchitectural  The  hippocampus  the limbic  malian b r a i n , erally  system.  Situated  i t curls  from  (sheep's  the f o l d i n g  arrangement.  i s a six-layered  and v e n t r a l l y  Ammonshorn  region.  toward  paleocortical  i n the temporal  the septal  nuclei  the temporal  of t h i s C - s h a p e d  cylinder.  lip  Excellent  presented  of t h i s  T h e names  T h e open f a c e o f a n -  the dentate gyrus,  structions  lat-  (sea h o r s e ) d e s c r i b e  o t h e r C-shaped c y l i n d e r , of t h e hippocampus.  l o b e o f mam-  caudally,  lobe.  h o r n ) and hippocampus  structure  abuts  t h e lower  three dimensional  recon-  r a t h e r complex a n a t o m i c a l a r r a n g e m e n t a r e  by H j o r t h - S i m o n s e n ,  1972; H j o r t h - S i m o n s e n ,  et a l . ,  1972;1975. Figure la diagramatically the hippocampal  region i n a horizontal  s e c t i o n s a r e used they In  clearly  i n anatomical  Figure l a these a r e i d e n t i f i e d  pyramidal pyramid  cell.  dendrites  r e g i o n because  l a y e r s of t h e hippocampus. by Roman n u m e r a l s .  are large  dendrites constitute  cell  Layer  type, the  (20-50 p. i n d i a m e t e r ) ,  from  the pyramidal  major d e n d r i t i c  l a y e r V.  cells  t r u n k s form  (layers  the stratum  lacunosum  eculare  i s made u p o f t h e s u p e r f i c i a l on t h e h i p p o c a m p a l  I I I and I I ) .  fissure.  T h e mass o f a p i c a l  constitute  stratum  border  Horizontal  s h a p e d , and g i v e o f f b o t h a p i c a l and b a s i l a r d e n d r i t e s .  basilar  their  section.  b o d i e s o f t h e major  These c e l l s  the appearance of  s t u d i e s of t h i s  show t h e s i x c o r t i c a l  IV c o n t a i n s t h e c e l l  The  illustrates  Layer  layer  I I I , and  r a d i a t u m , and I, s t r a t u m m o l -  d e n d r i t i c branches,  which  The axons of the p y r a m i d a l  - 5 cells  form a m y e l i n a t e d l a y e r ,  ition  to pyramidal c e l l s  are  present.  These  the alveus,  layer V I .  o t h e r s m a l l neurons  have been  elegantly  In a d d -  with short  illustrated  axons  by C a j a l ,  (1911) a n d L o r e n t o de Ntf ( 1 9 3 4 ) . A l s o shown i n F i g u r e pocampal  region:  dentata  referred  (F.D.)  to i n the l i t e r a t u r e  The arrows  in Figure  d a r i e s between C A l , CA2, a n d CA3. lished the  by L o r e n t o de No  basis  situated form.  other  hippocampal  modified the  Here  terminology of C a j a l  by C A l & CA2, r e g i o regio  inferior.  found  in literature The  Both  form.  o f CA4  patterns  observed i n o f CA4  (1956) a d o p t e d  the area occupied  a n d t h e a r e a o f CA3 and CA4,  i s basically  T h e s e have been  tightly  packed  indicated  layer  (GRL).  dendritic  region.  a simplification superimposed  i n Figure  o f t h e major  (10 u ) , r o u n d e r a n d more t i g h t l y o f a major  CA3  of t h e s e t e r m i n o l o g i e s a r e commonly  other.  Instead  m a t e r i a l on  The pyramids  (1911) who c a l l e d  I t has t h r e e l a y e r s  make u p t h e g r a n u l a r  stained  Blackstad  on t h e h i p p o c a m p a l  layers  d i v i s i o n s were e s t a b -  and t h e d e n d r i t e s  radially.  superior,  dentate gyrus  hippocampal  layering  areas i s lost extend  l a show t h e boun-  o f t h e d e n t a t e g y r u s a n d have a mod-  the discrete  pyramids  as the  of t h e p y r a m i d a l c e l l s .  than C A l pyramids.  in the hilus  ified  These  (1934) i n s i l v e r  of s i z e and a p p e a r a n c e  pyramids a r e l a r g e r are  of t h e h i p -  C o r n u ammon 1 (CA1), CA2, CA3, CA4 a n d t h e  dentate gyrus, often fascia  la are the subdivisions  cell  lb.  of t h e on each  S e v e r a l (6-8)  type, the granule c e l l ,  Granule c e l l s are smaller packed  than pyramidal  cells.  t r u n k , t h e y send m u l t i p l e  apical  - 6 d e n d r i t i c branches to No,  frontispiece), 1934).  The  up  from  the c e l l  and  they  have no b a s a l d e n d r i t e ( L o r e n t o  dendritic  superficially  to f i l l  l a y e r a r e two  t y p e s of  cells  with short The  the  of t h e g r a n u l e  molecular  neurons,  (compare F i g u r e l b  layer  displaced  cells  (MOL).  reach  Also in  granule c e l l s  z o n e c o n t a i n s numerous c e l l  to as the polymorphic  the granular layer  two  cell  layer  (POL).  t y p e s a r e t o be  t y p e s and is*  Immediately  below  found? those  their  of c e l l s w i t h  axons t o the a l v e u s .  cells  the molecular  is a  layer  layer  of t h e d e n t a t e  w i t h s h o r t axons which t e r m i n a t e  l a y e r , as w e l l as c e l l s Finally which  Next  a  layer  send  of s p i n d l e shaped c e l l s ,  The  division  t h e d e n t a t e g y r u s and  possibly  the d e n d r i t i c  A f f e r e n t s Connections  1911  dentate gyrus of  this  and  Lorento  i s through  input l i e i n the  and  (Cajal,  p a r t of  1911:  field  CA4  Laatsch layer  o f a r e a CA4  of  t o the D e n t a t e  de No,  1934).  The  the perforant path. lateral  entorhinal  & of  the  c h a r a c t e r i s t i c anatomical  marker.  Gyrus. through  of t h e d e n t a t e o r f r o m a c r o s s t h e h i p p o c a m p a l  (Cajal,  axons  polymorphic  F i b e r s to the dentate gyrus a r r i v e e i t h e r hilus  gyrus,  between t h e p o l y m o r p h i c  hippocampus has a n a t o m i c a l l y no  B.  send  w i t h axons d e s t i n e d f o r t h e a l v e u s .  t h e i r axons t o the a l v e u s  Cowan, 1 9 6 6 ) .  i n the  which  with  cells  into  this  and  axons t e r m i n a t i n g i n the g r a n u l a r l a y e r and  ascending  de  axons.  subgranular  referred  branches  body  the  fissure.  main i n p u t t o The cortex  cell  the  bodies  (A.E.) of  the  same h e m i s p h e r e ,  intervening  areas  7 -  and t h e i r  axons pass  ( t h e subiculum)  campus and c r o s s i n g  fissure  the outer two-thirds of t h e molecular ( L o r e n t o de No,  fibers  i n the p e r f o r a n t path  possibility  1934).  Cajal  has r e c e n t l y  S i m o n s e n & Zimmer  (1975).  the h i l u s  been  Using  fibers afferent from  contralateral  t h e fimbria.. hippocampus,  Commissural f i b e r s  from  c a m p a l commissure,  travel  the dendritic  one-third et  (1911) b e l i e v e d  some The  t h e e n t o r h i n a l area t o  investigated  degeneration  by H j o r t h -  techniques  to the r o s t r a l  dentate  to the dentate  gyrus a r r i v e  they  gyrus  pole).  Other  on  of the dentate  were i s s u e d c o n t r a l a t e r a l l y .  the dentate gyrus  (septal  to terminate i n  layer  o f a c r o s s e d pathway f r o m  d e s c r i b e a weak p r o j e c t i o n  (perforate)  before reaching the hippo-  t h e hippocampal  gyrus.  through  the midbrain,  area C M  branches  identification  and t h e septum.  the fimbria  of the g r a n u l e layer  techniques  of m i d b r a i n  hippo-  t o terminate  cells  i n the inner  ( B l a c k s t a d , 1956: R a i s m a n ,  R e c e n t l y , a n a t o m i c a l mapping  autoradiographic  from t h e  cross i n the ventral  through  of t h e m o l e c u l a r  a l . , 1965).  These i n c l u d e f i b e r s  through  o f pathways by  (Cowan, 1972) h a s a l l o w e d f o r t h e nuclei,  l o c u s c o e r u l e u s , a s an a d d i t i o n a l  the raphe source  n u c l e u s and t h e  of input t o t h e den-  I t a t e gyrus afferents  (Conrad,  e t a l . , 1974: S o e g a l ,  terminate  undescribed  source  i n the polymorphic of a f f e r e n t  n u c l e u s was o b s e r v e d jection essary  into  layer. from  by Sj^egal & L a n d i s  the dentate area.  to confirm  fibers  this.  e t a l . , 1973).  These  A previously  t h e suprama mmilary  (1974) a f t e r  Further studies w i l l  HKP i n be  nec-  - 8 Lesions cause  degeneration  gyrus. and et  i n the medial  a l . , 1973).  superficial  The exact cannot  studies.  resolve this  ambiguity.  C.  Intrinsic  Short  campus a r e known f r o m Lorento  de No,  1934).  of the s e p t a l  deduced  1971).  these  of t h e Dentate  c o n n e c t i o n s from  stains  Other  intrinsic  1971).  1911;  pathway  of t h e d e n t a t e  association  (Raisman, e t a l . , 1965; L a a t s c h & Cowan,  hippo-  (Cajal,  One of t h e s e , a n i p s i l a t e r a l layer  to  Gyrus  have been m e n t i o n e d b u t not s y s t e m a t i c a l l y  & Jeune,  existing  the i p s i l a t e r a l  studies using s i l v e r  CA3 & 4 p r o j e c t s t o t h e m o l e c u l a r (Zimmer,  from  (Mosko,  input t o the  T h e p r e s e n t work was u n d e r t a k e n  Connections  intrinsic  1966; Mosko e t a l . , 1973)  to the granule c e l l s  location  be c l e a r l y  degeneration  gyrus  zone of t h e dentate  (Raisman e t a l . , 1965; Raisman,  dentate gyrus  CAl  r e g i o n have been shown t o  i n the subgranular  i n a narrow band  from  septal  fibers  from  investigated  1966/ffj;orth-Simonsen  - 9 -  D.  Efferent  Connections  The  o n l y known o u t p u t  from  from  t h e axons of t h e g r a n u l e c e l l s , Along  t h e s e axons a r e l a r g e  bulbous  Before entering  t h e mossy f i b e r s  mossy f i b e r  (Cajal,  portions just  b o d i e s o f a r e a s CA3 a n d CA4  superior to  (regio  inferior).  The n a t u r e of t h i s  h a s been e x p e r i m e n t a l l y s t u d i e d by  B l a c k s t a d e t a l . , (1970).  They found  that  each  level  of t h e  d e n t a t e g y r u s p r o j e c t s t o no more t h a n a n a r r o w segment of  t h e hippocampus.  T h e s e segments a r e o r i e n t e d  to the l o n g i t u d i n a l a x i s of  the dentate gyrus  fibers.  There  of t h e hippocampus.  of  of the dentate gyrus  (1970).  transverse pole  b u t no mossy  inferior  Thus,  fibers  from  must  course  i n a temporal  T h i s may mean t h a t  t h e dentate gyrus  the regio  ju)  a r e , however, many mossy f i b e r s a t t h e t e m p o r a l  b e f o r e they t e r m i n a t e . connect  {-*500  The s e p t a l  c o n t a i n s many g r a n u l e c e l l s ,  p o l e of t h e dentate g y r u s . portion  1911).  t h e axons g i v e o f f s e v e r a l  the dentate gyrus.  projection  i s through  s w e l l i n g s and t h e a x o n s e n d i n  t h e hippocampus,  c o l l a t e r a l s within  Gyrus  t h e dentate gyrus  t e r m i n a l s on t h e d e n d r i t i c  the pyramidal c e l l  the Dentate  to different  the septal  t h e mossy  septo-tempora1  of t h e hippocampus  direction  fibers levels  ( B l a c k s t a d , et a l . ,  - 10  -  Figure l a H o r i z o n t a l s e c t i o n through t h e a r e a s CA1, the  CA2,  CA3,  CM,  hippocampal  and  region,  illustrating  the dentate gyrus  s i x l a y e r s of t h e hippocampus, and  to this  region  the f l m b r i a l  (F.D.), input  F.  Figure l b Enlarged here the  drawing  i s the v e r t i c a l  of r e c t a n g u l a r  i n 1A.  Illustrated  l a y e r i n g of dentate a f f e r e n t f i b e r s  d e n d r i t i c t r e e of a g r a n u l e c e l l ,  layer  area  of t h e d e n t a t e gyrus  (POL).  and  to the  onto  polymorphic  - 10a -  - 11 -  Figure l c Schematic drawing of  one  dentate  of a g r a n u l e  segment t r a n s v e r s e gyrus.  Broken  to the  line  cell  showing  the  l o n g i t u d i n a l a x i s of  depicts disputed  input.  circuitry the  Perforant path  lla  - 12 II  S y n a p t i c O r g a n i z a t i o n of t h e D e n t a t e A.  Laminar Arrangement  The  hippocampal  expresses a lb,  lc).  laminar  region along with  the dentate  organization i n three planes  In t h e h o r i z o n t a l p l a n e ,  r e g i o n s : C A l , CA2,  Gyrus  CA3,  CA4,  and  gyrus  (Figures l a ,  there are c l e a r l y  the dentate gyrus  different  (Figure l a ) .  T h e s e r e g i o n s a r e d e f i n e d a c c o r d i n g t o t h e a p p e a r a n c e of major  cell  differ is  types as  i n the l a y e r i n g  an a d d i t i o n a l  Layer  and  CA2  CA3  & CA4  bodies  a vertical axis The  the  incoming  the granule Along The  parallel  The  of these  there  superficial  association  hippocampal  layering  levels  of t h e i r  on  of  i n p u t s has  to  fibers i n CAl  fibers  from  inputs to  the  been d i s c u s s e d  nerve  terminals i s  of t h i s  segregated;  layering  they  the d e n d r i t i c  may  be  make s y n a p t i c t r e e and  soma  of  cell. the l o n g i t u d i n a l plane there i s a  segmental  hippocampal  in a  Bland,  formation i s arranged regard to i n t r i n s i c  Dudar,  1973).  t r a n s v e r s e to the l o n g i t u d i n a l  lamellae  i n CA3  i s more p r o m i n e n t  significance  signals are  lamellae with  (Andersen,  there i s a  layering  contacts at different  ment.  lacunosum,  source  shown i n F i g u r e l b . the  just  regions also  IV) where t h e mossy  i t contains i n t r i n s i c  S e c t i o n IB and  that  F o r example,  lucidum,  (layer  The  (the S c h a f f e r ' s c o l l a t e r a l s ) .  granule c e l l . in  inputs.  stratum  II, stratum  because  In  of  layer,  the pyramidal c e l l pass.  d i s c u s s e d i n S e c t i o n IA.  the  formation.  i s diagrammed  The  and  series  output  These l a m e l l a e are  circuitry  in Figure l c .  The  o f one  of  fibers  oriented  ( s e p t o - t e m p o r a 1) a x i s  basic  arrange-  of  of  the  these  extensive axonal  ramification dendrites ted  of  short  organization  B.  of  this  the  p r e and  onto s m a l l  and  neurons.  Type  than Type  I synapses are presynaptic  with  while  I  (300  (Uchizone,  (Robertson,  buffers  the  contacts  dendritic  are  trunks  narrower of  A)  (200 the  brain  spherical vesicles smaller  i n Shepherd,  ellipsoidal 1974).  explain  differences  same p r e p a r a t i o n . and  1976).  which  Bodian  found  The  by  T i s d a l e & Nakajima,  of a l d e h y d e f i x a t i o n  others  make  vesicles is affected  1970:  necessarily  Gray's Type  In many p a r t s  1965  flat  (1970)  some v e s i c l e s  were r e s i s t a n t t o f l a t t e n i n g i r r e s p e c procedure.  c e r t a i n v e s i c l e s are  fixation  A).  the  Gray's Type I I  I I with  of v a r i a t i o n i n w a s h i n g  b r a n e s of  1959).  I I have a somewhat  i n v e s i c l e shape i n the  flattened,  (Gray,  o c c u r on  between r o u n d and  examined v a r i a b l e s  in  associated  Type  However, t h i s d o e s not  tive  dense m a t e r i a l  e l e m e n t and  flattened vesicles  appear  synaptic  on  large  or  procedures  This  classified  with  the  fixation  orien-  be  associated  in  distinction  can  dendritic spines.  and  Type  the  cell  Terminals  a s y m m e t r i c a l appearance and  i n a p p e a r a n c e and  cleft  system a r e  the a n a l y s i s of  membranes  symmetrical  synaptic  onto g r a n u l e  longitudinal axis.  c e r e b r a l cortex  postsynaptic  dendrites  soma o f  the  of S y n a p t i c  d i s t r i b u t i o n of  I s y n a p s e s have an  (B)  region.  Ultra structure  of t h e  cells  mossy f i b e r  facilitates  Synapses i n the basis  the  strips across  l a m i n a r arrangement  -  axon basket  ( C a j a l , 1911), and  in parallel  13  (Bodian,  I t may  more s u s c e p t i b l e  1970).  Size  be  that  mem-  to a l t e r a t i o n  of v e s i c l e d o e s  not  -  appear  t o be a f f e c t e d  & Nakajima, their  1976).  by d i f f e r e n t  Isolation  close association  & Kuffler,  onto  layer  by e l e c t r o n  a r e commonly  electron-opaque  (700 - 1000 & i n d i a m e t e r )  t o monoamines s u c h  1970).  microscopy  i n the outer  of the dentate gyrus, a r e mainly  asymmetrical  & Cowan, 1 9 6 6 ) .  T h i s i s the d e n d r i t i c  t h e p e r f o r a n t p a t h and p o s s i b l y terminate  synapses  a r e found  wide a s y m m e t r i c a l contact  association  of t h e m o l e c u l a r  thickening? another  onto d e n d r i t e s .  The t h i r d from  r e g i o n where from C A l  terminate.  f i b e r s from  One t h a t  makes a  In t h i s  has a  symmetrical onto  r e g i o n t h e commissural  (Gottlieb  the i p s i l a t e r a l  A possible projection  been r e p o r t e d by some  t h r e e types of  makes c o n t a c t s o n l y  f r o m t h e c o n t r a l a t e r a l a r e a CA4  association  layer,  t h e main d e n d r i t e and v a r i e s i n  t h e t y p e of membrane t h i c k e n i n g .  others  shafts  fibers  ( L a a t s c h & Cowan, 1 9 6 6 ) .  small spines projecting  fibers  mol-  (Raisman, e t a l . , 1 9 6 5 ) .  In t h e i n n e r t h i r d  has  F o r example,  s p i n e s , a l t h o u g h a few a r e on main d e n d r i t i c  (Laatsch  and  has r e v e a l e d  (300 - 500 & i n d i a m e t e r )  t o a c e t y l c h o l i n e c o n t e n t and l a r g e r  Synapses observed  (Tisdale  substance (Eyzaguirre  1972).  n o r a d r e n a l i n and s e r o t o n i n (Bloom,  ecular  procedures  of t h e s e v e s i c l e s  1955 i n P a p p a s & P u r p u r a ,  synaptic vesicles as  fixation  with transmitter  electronlucent vesicles related  14 -  from  CA4  & Cowan, (Zimmer,  1973), 1971)  t h e septum t o t h i s  (Mosko, e t a l . , 1973) b u t not by  (Raisman, 1965: Cowan,  1975).  area  - 15 -  C.  Synaptic A c t i v i t y  i n the Dentate  In g e n e r a l i n p u t t o t h e d e n t a t e volley post  i n the p e r f o r a n t path  sequence  (Andersen,  plained  i n the f o l l o w i n g  action  potential  ulus.  The  through in has  firing  A depolarization  inhibition  been c o n c l u d e d  from  unit  through  basket  circuit  cells,  1966,).  accessible  to the p e r f o r a n t path  the basket  cells  molecular  cells  aptic  two  firing  of basket  cells  cells,  from  neuron  input as  It  granule  granule c e l l  i s not  axon  cells  directly  t h e d e n d r i t e s of  t o t h e o u t e r r e g i o n of  & Cowan, of  hippocampal  short latency response  e t a l . , 196i; ) .  the commissural  Stimulation z o n e s of  stim-  e x c i t e s the basket  back onto g r a n u l e  of t h e c o n t r a l a t e r a l  terminals i n the  (Gottlieb  extend  a high amplitude  (Andersen  c e l l s by  afferent  the  layer.  Stimulation produces  inhibitory  not  ex-  (EPSP) and  r e c o r d i n g s deep t o the  (Andersen,  do  The  The  can be  (IPSP) of t h e g r a n u l e c e l l .  t h e r e i s a feedback  collaterals,  the e x c i t a t o r y  collaterals.  (excitatory  characteristic  i n the b r a i n which  by  A  synaptic potential)  This i s a  of t h e g r a n u l e c e l l  produces  that  way.  i s produced  mossy f i b e r  turn,  layer  sequence  i s excitatory.  an EPSP-IPSP  post  et a l . , 1966).  excitatory-inhibitory  gyrus  elicits  synaptic potential-inhibitory  Gyrus.  This excitation  input i s mediated  inner t h i r d  by  area  CA3  i n the  granule  of t h e  granule  extensive  of t h e m o l e c u l a r  syn-  layer  1973). the medial  the dentate gyrus,  b l a d e s of t h e g r a n u l e  septum a c t i v a t e s c e l l s  apparently corresponding  layer,  as w e l l as  cells  in to  lying  two the in the  hilus.  This activation  temporal a x i s septal GA3  stimulation.  input  was  The and  cell  the  to septal  than t o  bodies  is a  since  from, he  nor  has  not  the c e l l  recorded could  layers.  identified  i n the response which  sectioning  response. supports both  and  this  the exact  t y p e , i t i s not  Raisman's  of the dentate  gyrus  agrees with both a u t h o r s '  f i n d i n g s of t e r m i n a l d e g e n e r a t i o n i n t h i s a r e a . Andersen  to  i n t h e septum  I I I B),  i n the h i l u s  stimulation  septo-  contralateral  the response  by A n d e r s e n  r e s p o n s e measured by A n d e r s e n Cells  along the  dentate response  that  (see S e c t i o n  d i d not a b o l i s h  Mosko's f i n d i n g s .  respond  described  from t h e c h o l i n e r g i c  fimbria  The  I t i s not c l e a r  p r o j e c t v i a the fimbria the  1961).  widespread  has a l o n g e r l a t e n c y  d e n t a t e gyrus which to  -  is fairly  (Andersen,  stimulation  16  layer  he  However  i s recording  c l e a r whether  h a v e come f r o m t h e s u p r a  since  the  response  or subgranular  - 17 -  III  The Septo-dentate A.  The Septum.  The  septum of the r a t l i e s along the m i d l i n e medial t o the  l a t e r a l v e n t r i c l e s and It  Pathway.  i s an elongated  just  r o s t r a l to the hippocampal r e g i o n .  s t r u c t u r e , widening  in a posterior  S e v e r a l groups of n u c l e i make up the septum & Stephan, 1964; Raisman, 1966).  direction.  (Young, 1936;  F i b e r s from the medial  Andy sep-  t a l and adjacent d i a g o n a l band n u c l e i have been i d e n t i f i e d p r o j e c t i n g t o the hippocampus 1966 ).  ( D a i t z & Powell, 1954;  These n u c l e i are bordered l a t e r a l l y by the  as  Raisman, lateral  s e p t a l nucleus, c a u d a l l y by the s e p t o - f i m b r i a l nucleus,  and  the v e n t r a l hippocampal commissure, d o r s a l l y by the d o r s a l s e p t a l nucleus, and a n t e r i o r - v e n t r a l l y by the nucleus accumbens. Raisman (1966) has d e s c r i b e d the e f f e r e n t septum using degeneration  techniques.  systems of the  These are  rostrally  d i r e c t e d f i b e r s t o the o l f a c t o r y t u b e r c u l e , the medial b r a i n bundle, and over the rostrum of the corpus The  fore-  callosum.  caudally d i r e c t e d f i b e r s include fimbria 1 a f f e r e n t s to  the hippocampus  and  dentate gyrus, a b i l a t e r a l  projection  i n t o the d o r s a l f o r n i x , f i b e r s passing t o the e n t o r h i n a l area through  the cingulum,  f o r e - b r a i n bundle, hypothalamus.  and  f i b e r s t o the habenula,  the  the l a t e r a l p r e o p t i c area and the  medial lateral  There a r e p r o j e c t i o n s t o the septum from  the  hippocampus, the p y r i f o r m c o r t e x , the amygdala, the o l f a c t o r y t u b e r c l e , the hypothalamus, and the m i d b r a i n .  Thus, the  septum makes e x t e n s i v e connections between the l i m b i c system  - 18 -  of  t h e c e r e b r a l hemispheres and t h e d i e n c e p h a I o n .  way  i n these connections  t a t e gyrus, which  A key p a t h -  i s the septal projection  makes e x t e n s i v e e x c i t a t o r y  t o t h e den-  synapses  o n t o key  r e g i o n s o f t h e d e n d r i t e s o f t h e CA3 and CA4 p y r a m i d a l (Raisman, 1966 ; S h e p h e r d ,  1974 ) .  These,  i n turn,  project v i a  c o n n e c t i o n s w i t h C A l n e u r o n s back t o t h e septum. dentate-hippocampal septo-hippocampal  B.  projection  the d o r s a l  (1961,  fornix,  nucleus  1963) showed t h a t  fibers  and a l v e u s . i n the medial  of t h e d i a g o n a l band. were f o u n d  a l . , 1969: Storm^rMathisen,  levels  Ach  intact  They a r i s e from septal  fimbria  n u c l e u s and i n  i n the supra-  h a s been c o l l e c t e d  when  e t a l . , 1967; McGeer,  inactivation  (DFP) i n t h e septum  Recovery  o f AchE  o f AchE by d i i s dependent  et a l . , 1974).  at the dorsal  l a y e r of  l a y e r s disappear  1970, 1 9 7 2 ) .  (Chippendale,  cells  of a c e t y l c h o l i n e s t -  w e l l marked  (Lewis,  i n t h e hippocampus a f t e r  isopropylflurophosphate an  acetylcholinesterase  Layers  T h e s e AchE p o s i t i v e  t h o s e pathways a r e i n t e r r u p t e d et  procedure,  l a y e r and l e s s d e n s e i n t h e i n f r a g r a n u l a r  the dentate gyrus.  direct  reach t h e hippocaropel f o r m a t i o n v i a  fimbria  erase p o s i t i v e s t a i n granular  septo-  Pathway.  s u r g i c a l and h i s t o c h e m i c a 1  b o d i e s which a r e s i t u a t e d the  to a  nature of the Septo-dentate  U s i n g a combined  (AchE)-containing  This  pathway.  Cholinergic  Shute & Lewis  i s in addition  cells  upon  Furthermore,  s u r f a c e of t h e h i p p o -  campus and t h e r e l e a s e c a n be i n c r e a s e d by s t i m u l a t i n g t h e  -  septum  (Smith,  medial  septum s t i m u l a t i o n  bria  but  not  1972).  by  The  sectioning  19  -  i n c r e a s e i n Ach was  a b o l i s h e d by  1968;  Direct  Bland,  evidence  septb-dentate  i s not a v a i l a b l e ,  suggests  evidence  would be  s u p p l i e d i f Ach  the dentate gyrus a f t e r  c o u l d be  C.  n u c l e i and  mimiced by  and  gyrus,  through  this  correspond  seen  generation granular  after  application  olution  acetylof  them  was  the  Direct  shown t o be  of Ach  released in  potential effect onto  i n t h e med-  produced  the  neuron.  i n the  septum t o t h e d e n t a t e g y r u s  the fimbria  that  completely septal  pathway  t o the h i l u s of AchE  lesions. One  zone of t h e d e n t a t e g y r u s , This thesis  Dentate  exists.  i s cholinergic  of t h e  dentate  i n the dentate  with t h e p a t t e r n of  have been o b s e r v e d .  of t h i s d i s p u t e .  this  Two  i s directed  gyrus  degener-  p a t t e r n s of  restricted the other  the  t h e above  case.  of t h e S e p t a l T e r m i n a l s  medial  s u p r a g r a n u l a r band.  for  ninety percent  i s the  single action  however t h e d i s t r i b u t i o n  d o e s not ation  a  that  i s considerable evidence  passes  of  although  i f the e l e c t r i c a l  Investigation Gyrus.  A pathway f r o m There  stain  i s the n e u r o t r a n s m i t t e r at  strongly  septal  fornix  (Dudar,  et a l . , 1974).  t h a t Ach  synapse  excited  evidence  ial  dorsal  the f i m -  fornix  Microiontophoretic application  choline to dentate granule c e l l s (Steiner,  sectioning  t h e a l v e u s or d o r s a l  1 9 7 5 ) , even though t h e a l v e u s and cholinesterase.  release after  to the  sub-  including towards a  de-  a res-  -  In o r d e r t o i d e n t i f y gyrus, a t r i t i a t e d  20 -  the s e p t a l t e r m i n a l s i n the dentate  amino a c i d  was i n j e c t e d  septum where i t was i n c o r p o r a t e d i n t o cell  protein  b o d i e s and t r a n s p o r t e d t o t h e n e r v e  dentate gyrus. either  light  techniques. the b r a i n  into  t h e medial  i n the septal  terminals i n the  T h e s e t e r m i n a l s c a n t h e n b e i d e n t i f i e d by  or e l e c t r o n  microscopy  using autoradiographic  T h i s t e c h n i q u e h a s been used  (Cowan, e t a l . , 1 9 7 2 ) .  t o map pathways i n  It has s e v e r a l  advantages  o v e r d e g e n e r a t i o n methods? a x o n s p a s s i n g t h r o u g h j e c t e d area  do not t a k e u p t h e l a b e l  a x o n s en p a s s a g e  are inevitably  s t r u c t u r e of t h e neurons  under  morphology  possible  to p r e f e r e n t i a l l y  varying This  study  label  injection  The f i n e  i s not a l t e r e d  by e i t h e r  d e p o s i t s , and thus,  c a n be a n a l y s e d .  t h e time from  i s because  (Cowan,et a l . , 1972) w h e r e a s  damaged by l e s i o n s .  d e g e n e r a t i v e changes or s t a i n i n g detailed  the i n -  With  nerve  this  their  method  i t  is  t e r m i n a l s o r a x o n s by  to s a c r i f i c e  o f two r a t e s o f a x o p l a s m i c  (Hendrickson,  flow? a f a s t  1972).  rate  w h i c h t r a n s p o r t s m a t e r i a l s t o t h e n e r v e t e r m i n a l s (20 - 1000 mm/day) and a slow  rate  (.5 - 2 mm/day) w h i c h  m a t e r i a l s a l o n g t h e l e n g t h o f t h e axon Three  days a f t e r  injection  terminals i n the lateral  injection in  6 6 % were i n a x o n s .  the present study  (Hendrickson,  silver  geniculate? thirty For the reasons  the  specific  septal  nerve  days  mentioned  the autoradiographic tracing  t h e whole s e p t o - d e n t a t e p r o j e c t i o n . : ,  Hendrickson  g r a i n s were i n  axoplasmic flow should provide a powerful t o o l tracing  1972).  i n t o t h e e y e o f t h e monkey  (1972) r e p o r t e d 5 3 % o f t h e d e v e l o p e d nerve  distributes  after above,  technique of  not only f o r  but f o r l o c a l i z i n g  terminals i n the dentate  gyrus.  - 21 -  METHODS  - 22 -  The  amount .of l a b e l l e d  injection  of t r i t i a t e d  was  measured by  was  to dissect  count  t i s s u e from  triated  after  a time  oplasmic  methods.  interval  transport.  Secondly,  medial for  septal  tribution be  methods.  the hippocampal  present  by  Finally,  injection  of  employed  fluid  liquid to  establish gyrus  of f a s t  i f labelled  labelled  of t r i t i a t e d by  this  layer  ax-  nerve  proteins i n the leucine  into  the  preparing brain sections The  relative  of t h e d e n t a t e  gyrus  discould  method.  the t y p e of nerve  t e r m i n a l w h i c h was  labelled  electron  microscopic autoradiography.  radioactive protein  phological description gyrus.  including  i n the dentate  necessary  observed  i n each  by  method  region  to the rate  entially  dentate  was  microscopic autoradiography.  determined  first  identified.  n u c l e i was  of l a b e l  nuclei  i n t h e t i s s u e by  corresponding T h i s was  The  after  septal  in scintillation  T h i s procedure  the d i s t r i b u t i o n  gyrus a f t e r  light  the medial  p r o t e i n s c o u l d be d e t e c t e d  t e r m i n a l s were t o be  dentate  into  prepare the t i s s u e  the r a d i o a c t i v i t y  scintillation that  leucine  t h r e e independent  the dentate gyrus, and  p r o t e i n s i n the dentate gyrus  was  prefer-  observed  by  T h i s p r o v i d e d a mor-  of t h e s e p t a l n e r v e  terminals i n the  23 . -  -  I.  Axonal T r a n s p o r t t o t h e Hippocampal  All  t h e r a t s used  i n this  Woodlyn Farms, O n t a r i o . grams were u s e d sport  s t u d y were  Twenty-one r a t s  t o i n v e s t i g a t e t h e time  of l a b e l l e d  Region.  male r a t s weighing  from  290-320  course f o r the t r a n -  p r o t e i n a l o n g t h e axons' o f t h e s e p t o h i p p o 3  campal pathway.  .35 uC o f  specific activity cerebrospinal Stereotaxic fitted at  (pH 7.4) was i n j e c t e d  lateral  sacrificed Rates  needle  of a r t i f i c i a l  over  into t h e medial  c o o r d i n a t e s taken 0.0 mm? and d o r s a l  by c e r v i c a l  20 m i n u t e s .  f o r fast  axonal  axonal  axonal transport  slow  transport  days.  to  sacrifice  i n order t o l a b e l  by  t h e u s e of t h e above times  of  24 h o u r s . T h e b r a i n s were  kept  n u c l e u s , and h i p p o c a m p a l In o r d e r t o i n v e s t i g a t e  transport  were  and 4 days.  o f .5 - 2 mm/day.  i n r a t i s 4 - 5 mm i n l e n g t h , within  s i x hours, and  The o p t i m a l time from  injection  n e r v e t e r m i n a l s was i n v e s t i g a t e d plus a third  i n t e r m e d i a t e time  on i c e w h i l e t h e septum, r e g i o n were d i s s e c t e d  caudate  out f r e e  hand.  i f t h e septum p r o j e c t e d d i f f e r e n t i a l l y  t h e length of t h e l o n g i t u d i n a l a x i s  the hippocampal  nucleus  have been e s t i m a t e d o f  c o u l d be expected  i n four  syringe  the earbars: anterior  3.5mm.The a n i m a l s  transport  S i n c e t h e s e p t o - d e n t a t e pathway fast  from  septal  f r a c t u r e a t 6 a n d 24 h o u r s ,  20 - 1000 mm/day a n d f o r s l o w  along  Nuclear,  i n j e c t i o n s were made u s i n g a 10 u l H a m i l t o n  w i t h a 34-guage  mm?  (New E n g l a n d  38 C i / m mole) i n .5 u l i t e r  fluid  the following  8.9  H-leucine  r e g i o n was d i v i d e d  into  of t h e dentate  two e q u a l  gyrus,  anterior  -  and  posterior  dorsal  The cold  10% TCA,  p r e c i p i t a t e was  tillation rest  t i s s u e was  c e n t r i f u g e d a t 600 resuspended  fluid  was  m i x t u r e and  solved.  resuspended  .25  by  were added  s a m p l e s c o o l e d f o r 60  counting f o r 4  two v i a l s  tillation  mix,  for  each  with  2 drops  level  sample and  =  (cpm  - B)  counts .25  cpm  the  the scin-  counting.  protein  until  dis-  were t h e n mix? 2  drops  chemilluminescence  b e f o r e c o u n t i n g by  ml  o f HAc  o f 23  r a t i o n s p e r m i n u t e by dpm  left  the  liquid  and scin-  minutes.  of b a c k g r o u n d  preparing  background  each  scintillation  to decrease  minutes  of  ml.  for 5  scintillation  ml of t h e s o l u e n e - p r o t e i n s o l u t i o n  acetic acid  and  toluene-based  i n .5 ml s o l u e n e and  of  level  .5 ml  d i s c a r d e d and  of t h e t o l u e n e - b a s e d  A  the  in 2  centrifuged  tissue,  liquid  a d d e d t o 10 ml  tillation  and  a d d e d t o 10 ml o f a counted  homogenized  g . for- 5 m i n u t e s  i n 5% TCA  of t h e s u p e r n a t a n t was  s a m p l e was  the  ( t e m p o r a l ) p o l e of  weighed and  In t h e c a s e o f t h e s e p t a l  supernatant  The  the v e n t r a l  to  region.  dissected  minutes.  -  these p o r t i o n s corresponded  ( s e p t a l ) p o l e and  hippocampal  of  portions,  24  m i n u t e was  of s o l u e n e ,  and  was  per  cooling  obtained  10 ml  of  t h e cpm  r e s u l t i n g value converted to  the following • DF  scin-  them f o r 1 h o u r .  s u b t r a c t e d from  by  This  obtained  disinteg-  method:  . E  where: dpm  = disintegrations  B  =  DF  = dilution  E  = efficiency  per  minute  background factor  ( i . e . .25  ml o f  .5  ml  solution  o f c o u n t i n g = 20% f o r H - l e u c i n e . 3  counted)  - 25 The  r e s u l t i n g dpm  analysed  were d i v i d e d  f o r e v i d e n c e of  by  tissue  transport.  weight  (mg.)  and  - 26  II  Light  -  Microscope Autoradiography  of t h e D e n t a t e  Gyrus.  i Sixteen  r a t s were p r e p a r e d f o r l i g h t 3  r a d i o g r a p h y by  injecting  2 uC  of  H-leucine  ^ m o l e ) i n .5 j u l of a p h o s p h a t e - b u f f e r e d 40  minutes  anterior, center.  stereotaxically o.oo  One  this brain  mm  into  lateral;  a n i m a l was  4.0  not  a n a e s t h e s i z e d w i t h Nembutal f u s i o n w i t h 4% of  The for  a minimum of one  emulsion, for  mounted  t i s s u e was mixed  5 hours,  gently  dark  from  the  9.1  over mm  earbar tissue  from  10 d a y s t h e a n i m a l s  were  preceded  l a b e l and  by a  on  killed  by  per-  .9% s a l i n e  and  rinse  in either  solution,  fixed  Both  formald-  control  d r a i n e d i n the Exposure  stained  hor-  and  w i t h Kodak NTB  i n Kodak R a p i d  r u n n i n g w a t e r o v e r n i g h t , and  illumination  i n 2%  3  dark  t i m e s of  b e f o r e t h e g r a i n s were d e v e l o p e d  f o r 3 minutes,  field  to sucrose  a c o r o n a l or  kept  red s a f e l i g h t  packaged f o r s t o r a g e .  counts  in perfusate  transferred  microtome and  with Dreft  Grain  left  clean glass s l i d e s .  c o a t e d under 1:1  out and  week b e f o r e b e i n g  weeks a t 4° C were u s e d Kodak D-19  septum,  (50 mg/kg), and  dissected  i z o n t a l p l a n e on a f r e e z i n g  test  1 and  25um s e c t i o n s were c u t  ehyde u n t i l  dorsal  (pH 6.5)  system.  whole b r a i n was  formalin.  At  formal saline,  the v a s c u l a r  the medial mm  ( s p . a . = 38 C i /  solution  injected with  used a s c o n t r o l .  microscopic auto-  3-4  with  F i x , washed i n  with  cresyl  violet.  o f t h e whole hippocampus were made u n d e r on a Z e i s s L i g h t  microscope.  Each  of  t h e t h r e e l a y e r s o f t h e d e n t a t e g y r u s were a n a l y s e d f o r a r e a s 2 of  2600 u  which  includes the molecular  layer,  the g r a n u l a r  -  l a y e r and t h e p o l y m o r p h i c wings of t h e dentate 3-4  slides  fibers. cortex  from  27 -  region  of t h e d e n t a t e h i l u s .  f o r both hemispheres  were c o u n t e d  Both on  three r a t s f o r the a n a l y s i s of septo-dentate  C o n t r o l a r e a s were t a k e n f r o m o f t h e same  slides.  layer  3 of the e n t o r h i n a l  - 28 III  E l e c t r o n Microscope Terminals. Eleven  r a t s were  Autoradiography  injected  of t h e S e p t a l Nerve  with e i t h e r  2uC o r 4.5 uC o f  3 H-leucine  i n the medial  septum o v e r 40 m i n s .  r a t s were p r o c e s s e d a s c o n t r o l a n i m a l s . after  injection  aldehyde,  Two u n i n j e c t e d  Twenty-four  t h e a n i m a l s were p e r f u s e d w i t h 4%  hours  paraform-  o.5% g l u t a r a l d e h y d e , and 0.54% g l u c o s e i n 0.1  M 3  phosphate  buffer  (pH 7.4) u n d e r N e m b u t a l a n a e s t h e s i a .  c u b e s were d i s s e c t e d was  then  left  i n aldehyde  buffer,  post-fixed  hours)?  dehydrated,  Gold  f i x a t i v e f o r 2 hours,  w i t h b u f f e r e d osmium a n d embedded  carbon  prepared  Ilford  d r a i n and p a c k a g e d After  Microdol-x  (Rogers,  with  lead  for synaptic  or R e i c h e r t microtome  grids for classification  o r on  was a p p l i e d  t h e g r i d s were l e f t  to the grids  loop technique  f o r t h r e e hours t o  t h e s e c t i o n s were d e v e l o p e d 1967) o r D-19  citrate.  r a d i o g r a p h y were s t a i n e d  formvar  T h e s e c t i o n s were not  L-4 e m u l s i o n  p r o c e s s e d a t t h e same t i m e .  thick  (1% f o r 2  f o r storage in black l i g h t - t i g h t  6 t o 12 weeks,  minutes  tetroxide  f o r a u t o r a d i o g r a p h y by t h e s t a n d a r d  under r e d s a f e l i g h t ,  tissue  rinsed in  or s i l v e r - g r a y  f o r autoradiography.  coated.  The  i n an e p o n - a r a l d i t e m i x t u r e .  were c u t on e i t h e r a LKB  mounted on u n c o a t e d  coated g r i d s  lu  the dentate gyrus.  sections f o r autoradiography  classification and  out from  1mm  boxes.  in either  f i x e d and s t a i n e d  U n i n j e c t e d m a t e r i a l was  f o r 10 also  S e c t i o n s not i n t e n d e d f o r a u t o -  w i t h b o t h u r a n y l a c e t a t e and l e a d  s e c t i o n s were c u t f r o m  blocks taken  from  citrate,  the dentate  gyrus  - 29 -  and  stained  with t o l u i d i n e blue.  the granular c e l l  layer  were u s e d  S e c t i o n s were o b s e r v e d  2400 &  500 g r a i n s were c l a s s i f i e d  occupied  by e a c h  occupied  more t h a n h a l f  uted  t o that  structure  structure,  201 o r 300  electron  according to the  I n t h e c a s e where t h e g r a i n  two or more s t r u c t u r e s a c i r c l e (Bachmann & S a l p e t e r ,  of t h e dentate  f o r autoradiography.  on a P h i l i p s  structure underlying the grain. overlay  t h e s e b l o c k s i n which  and p o l y m o r p h i c a r e a  g y r u s c o u l d be i d e n t i f i e d  microscope.  Only  w i t h a r a d i u s of  1965) was drawn and t h e a r e a  determined.  of t h e c i r c l e  I f one the grain  otherwise p r o p o r t i o n a l  structure was  attrib-  probabilities 2  were a s s i g n e d t o e a c h  structure.  An a r e a  the t h r e e l a y e r s of t h e dentate gyrus grain ted  c o u n t s were p e r f o r m e d  x 2h, and a r e a  These area grain  were u s e d This  and  to c l a s s i f y  classification  vesicle  measurements done on e a c h  f o r each  tissue  to calculate Fifty  prin-  component.  the r e l a t i v e  labelled  synapses synapses.  was done on t h e b a s i s o f  shape, d i s t r i b u t i o n  of post s y n a p t i c  on w h i c h  a t x 8300,  s y m m e t r i c a l and a s y m m e t r i c a l  of synapses  size, vesicle  thickening  structure.  covering  from a s e c t i o n  was p h o t o g r a p h e d  measurements were u s e d  density  o f 4400 u  membrane.  pattern  of v e s i c l e s ,  - 30 -  -  I.  Axonal Transport  In t h i s vation  part  of the  31  to the  of  the  Hippocampal  study  i n j e c t i o n s i t e was out  dissected  the  r a d i o a c t i v i t y incorporated  animals studied low  and  had  not  activity  i n the  injection  site  n u c l e u s b o r d e r s on  counts  in this  caudate.  analysis  poles  of  the  was  of t h e  the  would be  since nearby  the  hippocampal  the  i n the  poles At  was the  l e u c i n e was dicating  end  no due  in Table  was  i n the  t a k e n up  by  the in  the  posterior If  to d i f f u s i o n rather  no  (septal)  difference,  higher  of p r o t e i n s from the  in-  than  and  in  the  hippocampal region from t h e  a n t e r i o r and  were  septum  to  posterior  I.  s i x hours the a c t i v i t y  most of  grain  i n the a n t e r i o r  there  the  caud-  differences.  hippocampus was  Data  considerably  that  septum was  of  was  counts  to axonal transport  pooled  showed  region  counts  hippocampal r e g i o n .  Low  measured  i n t h e a n t e r i o r and  Since  caudate nucleus,  attributed  a  from  diffusion into  the a c t i v i t y  higher  expected.  activity  material  ex-  r e s u l t of d i f f u s i o n s i n c e an  counts  than axonal transport, pole  i n d i c a t e d no  hippocampal region  i n the  tritiated  of  All  T h i s was  lateral ventricles.  It i s u n l i k e l y t h a t  itial  activity  the  septum  counting  l a t e r a l v e n t r i c l e s because the  structure  hippocampal region  s i n c e the  i n s e p t a l n u c l e i , and  caudate nucleus.  c o n t r o l f o r seepage of i n t o the  obser-  into septal proteins.  necessary  ate  possible  prepared f o r s c i n t i l l a t i o n  high  activity  Region.  direct histological  was  tremely  -  lower than t h a t  the the  tritiated cell  attributed to i n the  leucine  b o d i e s and  free  protein i n -  injected into incorporated  the  into  - 32 -  TABLE 1 TIME COURSE OF AXONALLY TRANSPORTED H-IEUCINE LABELLED PROTEINS AFTER INJECTION INTO MEDIAL SEPTUM.  Number  Mean (dmp/mg)  S.D.  6 Hours Hippocampus  21  11.35  6.33  Septum  4  620.75  313.88  Unbound l e u c i n e  5  75.73  Caudate N u c l e u s  2  <1  24 Hours Hippocampus  21  25.54  18.37  Septum  6  954.24  256.66  Caudate N u c l e u s  5  <1  4 Days Hippocampus Septum Caudate N u c l e u s  22 . 6 13  69.48  25.98  666.54  184.18  <1  - 33 -  protein. In  order t o determine  tritiated  l e u c i n e from  t h e time course o f t h e t r a n s p o r t of  t h e septum t o t h e h i p p o c a m p a l  r a d i o a c t i v e material appearing ing  protein any  i n t h e hippocampal  t i m e up t o s i x h o u r s .  than a t twenty-four the a c t i v i t y  twice as fast  the counts fast  has  injection  that  a t s i x hours  edge o f a v e r y  5 mm/day.  e s t i m a t e f o r slow  hours  Since  . 5 - 2 mm/day nerve  t o be l a b e l l e d leucine  this  transport,  days t o slow  In o t h e r p a t h w a y s s l o w a x o n a l  that  rapid  c o u l d be a t t r i b u t e d t o  and t h e counts a t f o u r  indicate  of t r i t i a t e d  t r a n s p o r t had  edge o f a peak w h i c h was  of approximately  been e s t i m a t e d t o b e f r o m  g y r u s may be e x p e c t e d  of t r i t i a t e d  t r a n s p o r t e d was l o w e r  the t a i l i n g  seen a t t w e n t y - f o u r  These r e s u l t s  I shows t h a t  I t would a p p e a r  as the fastest  (1 mm/day).  e s t i m a t e s of 20 - 1000  t h e appearance  b u t t h e amount  or the leading  axonal transport,  transport  Table  hours.  at a rate  vary-  r e g i o n c o u l d have been e x p e c t e d a t  s e e n was e i t h e r  peak o f t r a n s p o r t , transported  Using  axonal transport,  occurred a t s i x hours  was  i n t h e hippocampus a f t e r  s u r v i v a l t i m e s was a n a l y z e d .  mm/day f o r r a p i d  region,  transport  (Hendrickson,  1972).  terminals i n t h e dentate  t w e n t y r f o u r hours  after  i n t o t h e septum o f t h e r a t .  - 34 -  II.  D i s t r i b u t i o n of Label in the Dentate Gyrus. In order to analyse which layer of the dentate gyrus  receives the septal input, as indicated by the presence of s i l v e r grains after autoradiographic processing of the tissue, horizontal sections of the hippocampal region were taken.  The  three layers could be seen d i s t i n c t l y in horizontal section (Figure l a , l b ) .  In a photograph of the i n j e c t i o n s i t e of  one of the animals used in the analysis, heavy radioactive l a b e l l i n g could be seen in the medial septal nuclei (Figure 2a).  The density of l a b e l in t h i s region was considerably  higher than in the neighbouring l a t e r a l septal nuclei although d i f f u s i o n to these areas could not be discounted.  At the  l i m i t s of the septal nuclei bordering the l a t e r a l v e n t r i c l e , d i f f u s i o n was minimal.  This can be seen in Figure 2a and was  supported by the low grain counts observed in an area of the caudate nucleus (CN) adjacent to the v e n t r i c l e (Figure 3 ) . Heavy l a b e l l i n g was seen in the myelinated axons of the fimbria 1 pathway (Figure 2 b ) .  It could be seen that the por-  t i o n of the fimbria which borders on the l a t e r a l v e n t r i c l e (lower l e f t ) portion.  i s much more heavily labelled than the medial  Thus, there i s a regionalization of the  septo-dentate  f i b e r s in the f i m b r i a . In the hippocampal region grain counts were done on the three layers of the dentate gyrus and the supropyramida1 (stratum radiatum, S t . R.) and the subpyramidal (stratum oriens, 0.) of the hippocampus.  Labelling was seen in both these  St.  -  l a y e r s of CA3,  but  not  s t u d i e s by Raisman, observed  layer  campus.  Both  gyrus a  layer  granular gyrus, morphic  layer  clearly  be  area no  layer  (PL) a r e by  significant  be  w h i l e the grain This  seen,  result  on  hippo-  dentate  i n the  i n F i g u r e 2c.  subdentate poly-  It could  F i g u r e 2c w i t h F i g u r e 4b,  cortex  an  (A.E.) of t h e same r a t , t h a t  occurs i n the molecular  layer.  F i g u r e 4a  em-  H e r e t h e t i p of t h e m e d i a l wing  i s shown.  The  same p a t t e r n o f  zone  (right  (left  w i t h Raisman's results  of  labelling  side) i s labelled,  s i d e ) i s not.  these zones confirmed  (1975) u n p u b l i s h e d  of the  In t h e  observed  was  included the  g r a n u l a r l a y e r ( G L ) , and  the subgranular  agrees  labelling  t h r e e l a y e r s of t h e  indicated  s u p r a g r a n u l a r zone  counts  was  degeneration  this CA4  i s shown i n F i g u r e 4 b .  finding.  the d e n t a t e gyrus could  (ML),  labelling  labelling  phasized t h i s  The  comparing  i n the e n t o r h i n a l  Background  labelling  with  highest  r e g i o n s were l a b e l l e d .  (Figure 2c).  seen  The  of the d e n t a t e gyrus,  of heavy  molecular  i n agreement  of t h e d e n t a t e g y r u s and  these  zone  i n CAl,  -  e t a l . , 1965.  i n the h i l u s  polymorphic  35  the observed  Furthermore, result.  (1965) f i n d i n g s and  Cowan's  using autoradiographic a n a l y s i s  of a x o n a l l y t r a n s p o r t e d m a t e r i a l ,  but  not w i t h Mosko's  (1973).  - 36 -  III.  Ultra structure  In  of S e p t a l T e r m i n a l s .  order to i d e n t i f y  which s t r u c t u r e s  zone of t h e d e n t a t e gyrus silver for  zone.  labelling synaptic  A RGD of t h a t  density  structure.  zone.  pass  glia  but l e s s  through  a r e not  so than  by  More s y n a p s e s  this  account of  preferential  the h i l a r synapses.  not l a b e l l e d  labelling.  axons  the s e p t a l  neurons.  do  Dendrites  C e l l b o d i e s and  which  cells),  (e.g. synapse  the l a t t e r cases  synapse  "en p a s s a g e "  dentate  gyrus.  Asymmetrical  types of  synapses  boutons  formed  o r were p r e s e n t  i n such  small  they  seen w i t h t h e l i g h t  passing through  onto  elements  fiber  i s shown i n F i g u r e 5.  labelled.  dendritic  "en p a s s a g e " ) t h a t  synapses  i s labelled i s  Other  ( e . g . , t h e mossy  f o r the l a b e l l i n g  most h i g h l y  than  r e g i o n , but i n f a c t ,  T e r m i n a l s y n a p t i c boutons onto  t h e axons of g r a n u l e  quantities  significant  labelled.  showed h i g h l y were e i t h e r  II gives  structures in  one i n d i c a t e s  In T a b l e I I I , t h e t y p e o f s y n a p s e presented.  processed  Table  T h i s indicates that  make s y n a p t i c c o n n e c t i o n s w i t h labelled  z o n e were  by  S i l v e r g r a i n s were l o c a l i z e d i n  (RGD = 1 . 7 2 ) .  in this  a x o n s do n o t s i m p l y  are  this  (RGD), f o r s e v e r a l  of g r e a t e r than  structures  were l a b e l l e d  from  labelled  microscopic autoradiography.  the r e l a t i v e g r a i n this  were p r e f e r e n t i a l l y  g r a i n s , b l o c k s of t i s s u e  the electron  i n the subgranular  c o u l d not  microscope.  This i s a  the n e u r o p i l  One  labelled  of t h e  d e n d r i t e s o r s p i n e s were t h e  Of t h e s e a s y m m e t r i c a l  synapses,  fifty  -  percent  were o n t o s p i n e s  This  t y p e was  the  37.4%  of t h e  total  can  be  seen t h a t  300  A with  and  (50  synaptic - 500  the  boutons  the  former  rical in  on  6c,  was  the  s i d e s of  and  as  and  for this  be  classified  reason, as  the  of  (300  it  200  -  - 600  &  thick-  junction  is slightly  convex  The  pre-  l u c e n t v e s i c l e s of packed  h a l f as  throughout  frequently  h e a v i l y - l a b e l l e d as This  i s narrower  dense m a t e r i a l  As (50  Several  s m a l l v e s i c l e s (300  The find  &  symmetrical  was  be  arranged an  A* i n d i a m e t e r ) present  j u n c t i o n s are as  a  junctions  b o u t o n s might  synapses i n the  seen  A)  marked by  the asymmetrical  some p r e t e r m i n a l  pre-  - 100  d i a m e t e r ) were  symmetrical than  could  symmetrically  density  - 1000  the  as  s y n a p s e made symmet-  This  to  6b,  presynaptic  moderately  cleft  some l a r g e v e s i c l e s (700  r u l e more d i f f i c u l t  cleft  cleft.  nerve t e r m i n a l .  and  6b).  not  synaptic  6c.  occupying  defined  round e l e c t r o n  nerve t e r m i n a l .  the  6a  thickening  onto major d e n d r i t i c t r u n k s .  in Figure  the  region,  synaptic  synapse occurred  b r o k e n p a t c h e s of  arrow  in  t y p e and  contacts  both  with  type of  described  Figure  with  ( F i g u r e s 6a  dendrites.  i n t r u s i o n s or e x t r u s i o n s .  A" d i a m e t e r w h i c h a r e  second  viously  clearly  The,synaptic  without  hilar  postsynaptic but  number o n t o  In F i g u r e s  bouton forms a  structure contains  400  A  the  $).  presynaptically  half that  synaptic area.  a finer  - 100  and  -  common i n t h e  a pronounced  thickness) ening  most  37  possibly*  present  an-  alysis. These r e s u l t s represent structures  of  the  n e u r o p i l of  the the  pattern  of  subgranular  labelling zone of  in the  the  - 38 -  dentate gyrus a f t e r septal  nuclei.  i n j e c t i o n of t r i t i a t e d  material  into  the  - 39 -  TABLE I I DISTRIBUTION OF SILVER GRAINS IN DENTATE GYRUS AFTER  3  H LEUCINE INJECTION INTO MEDIAL SEPTUM RGD % grains/ % area  Area  %  26.9  661.5  15.6  1.72  104  20.7  777.0  17.7  1.17  axon  194  38.6  1777.1  40.6  0.95  soma  55  11.1  752.3  17.1  0.64  glia  12  402.0  9.2  0.26  4369.6  100.8  Structure  No. O f gra i n s  %  synapse  135  dendrite  Total  500  Of  gra i n s  2.39  99.7  Of  area  -  - 40 -  TABLE I I I DISTRIBUTION OF SILVER GRAINS IN THE SYNAPSES OF THE DENTATE GYRUS No. of gra ins  Structure  % of gra i n s  Area M  % of area  RGD % gra i n s / % area  ,axo-dendritic or axo-spinous synapse 1) asymmetrical  75  55.6  247.7  37.4  1.49  2) symmetrical  29  21.5  107.6  16.3  1.32  5  3.7  1.5  0.2  6  4.4  29.0  4.4  1.00  12  8.9  13.5  2.0  4.45  8  5.9  262.2  39.7  0.15  135  100.0  661.5  100.0  3) u n c l a s s i f i e d axo-somatic  synapse  synapse en passage mossy f i b e r  Total  bouton  - 41 -  DISCUSSION  - 42 -  Interpretation with caution. be  In t h i s s t u d y  medial s e p t a l  The f i r s t ,  m i s s u r e d i d not i n c o r p o r a t e labelling  are  was s e e n  campus.  i n t h e i r study.  d o r s a l and v e n t r a l either  hippocampus  autoradiography.  This  observation in  transport  the l a t e r a l  to  t h e d o r s a l and v e n t r a l The  septal a  decreased  and  transported  in labelling were f o u n d  in this  along  that  be a t t r i b u t e d septum a n d  times  However,  the density  of l a b e l l i n g  l e s s than  i n the medial  i n t h e amounts  evidence that  t h e axon  study  microscopic  transported  be  detected.  r a d i o a c t i v i t y of t h e supernatant  i n protein,  (septal  between t h e  a light  hippocampus c o u l d  n u c l e i supports other  common amino a c i d  hippocampus  into the lateral  2a r e v e a l e d  no d i f f e r e n c e  The  of r a d i o a c t i v i t y i n the hippo-  septum was s e v e r a l  septum, a n d s t i l l  such a  pole).  t o the v e n t r a l hippocampus.  of F i g u r e  nucleus  t o the hippo-  of d i f f e r e n c e could  leucine  no e v i d e n c e  septal  (temporal  c o u n t s done u s i n g  lack  seepage of t r i t i a t e d  subsequent  counting  com-  l a y e r where t h e s e f i b e r s  t o the d o r s a l  hippocampal region  or by g r a i n  to the  (1971) i n d i c a t e d  No d i f f e r e n c e s  by s c i n t i l l a t i o n  campal r e g i o n  to  since  by R a i s m a n , 1966 not t o p r o j e c t  medial s e p t a l n u c l e i projected pole)  to project  The second, t h e l a t e r a l  t o the v e n t r a l  cannot e n t i r e l y  w h i c h b o r d e r on  labelled protein  However, S i e g e l a n d T a s s o n i  projection  must be done  the v e n t r a l hippocampal  i n the molecular  known t o p r o j e c t .  was r e p o r t e d  two s t r u c t u r e s  n u c l e i have been r e p o r t e d  hippocampal r e g i o n .  of  labelling  D i f f u s i o n from t h e i n j e c t i o n s i t e  eliminated.  the  of a u t o r a d i o g r a p h i c  tritiated  i s incorporated (Droz,  1969).  into  There  from t h e leucine, protein appears  - 43  t o be al., 48  two  r a t e s of t r a n s p o r t  (1974) o b s e r v e d  hours a f t e r  with  i n nerve  (Grafstein,  1967;  The  that  was  1972)  who  r e g i o n , w i t h S h u t e and erase p o s i t i v e f i b e r s Andersen,et septal  Lewis  al.,(1961) who  observed  A  seen  i n the h i l u s  (1961) who  terminals in this observed  dense  i s the cutting  commissure w h i c h  lies  terminate i n the supragranular layer  the l e s i o n ,  label,  of passage  layer  of  neurons  silver  this  ( 1 9 6 5 ) , Cowan,  obvious  through  could r e s u l t The  a r e not a f f e c t e d  by  (1975) j  of  i n the v e n t r a l  this  septum.  commissure  of these f i b e r s i n t h e type of  were  degen-  autoradiographic tracing  to degeneration studies  (cowan, e t a l . , 1 9 7 2 ) .  source  gyrus.  where Mosko e t a l . ,  I f e v e n a few  these authors.  technique i s superior fibers  from C A l pass  degeneration.  by  of h i l a r  with  caudal to the medial  and  observed  cholinest-  h e r e , and  of f i b e r s  commissural  eration  fibers  An  The  damaged by  and  i n t h e s u b g r a n u l a r zone of t h e dentate  i n Mosko's s t u d y  (1973) f o u n d  the  v  recorded responses moderately  of  et a l ( 1 9 6 5 )  t h e septum e n d i n g  not w i t h Mosko, e t a l . , ( 1 9 7 3 ) .  hippocampal  as  rapidly transported  i s i n agreement w i t h Raisman, e t a l . ,  error  Reports  nerve t e r m i n a l s .  degenerating  from  stimulation.  g r a i n s was  saw  protein  twenty-four  confirm  that  -  T h i s agrees  labelled  T h i s i s i n agreement w i t h Raisman v  but  label  heaviest l a b e l l i n g  Mosko e t a l ( 1 9 7 3 )  This  t h e septum.  study  et  i n t h e hippocampus 16  findings also  Hendrickson,  materials preferentially  dentate.  from  Chippendale,  t e r m i n a l s of t h e d e n t a t e g y r u s  injection.  to  AchE a p p e a r e d  of t h e p r e s e n t  hours a f t e r  The  along the axon.  i t s disappearance  the f i n d i n g s  arrived  that  -  in this  the injection  regard of  - 44  -  Acetylcholinesterase-positive granular ed by  zone o b s e r v e d  the present  axons w h i l e t h i s are  not  by  Shute  findings. study  in conflict.  & Lev;is  But  looked at The  nerve  fibers  i n the  (1963) a r e not  as they  m a j o r i t y of  nerve t e r m i n a l s , the  silver  g r a i n s observed  terminals.  be a t t r i b u t e d  t o some o f t h e l a b e l l e d  cleft.  Evidence  t e d by G r a f s t e i n is  Two  t y p e s of  subgranular as  Silver  that  (1967) and  needed t o u n d e r s t a n d  zone,  afferents. metrical  Hendrickson  labelled  synapses  an a s y m m e t r i c a l  In t h i s  thickening  t y p e of v e s i c l e s  minal  i s seen  the density  septum and i s that  i s half  of l a b e l  that  i n the  ascribed  o t h e r t e r m i n a l c o u l d be  ment a g a i n s t t h i s  in the  of t h e s e  that  labelled  (Hattori  round  boutons  in  morphological nerve  of l a b e l  the dentate.  1974).  diffusing One  w i t h which t h i s  of t h e o t h e r l a b e l l e d  i n the l a t e r a l  septal  & McGeer 1973,  the r e s u l t  the frequency  nerve  t h e asym-  to c h o l i n e r g i c  labelling  twice  the c h o l i n e r g i c  well with the  i n the r a t neostriatum  the l a t e r a l  this.  o f t h e p o s t s y n a p t i c membrane and  characteristics previously  into  One  the  F u r t h e r work  t y p e o c c u r i n g about type.  may  been r e p o r -  were o b s e r v e d  r e g a r d , i t i s noteworthy  the dentate gyrus corresponded  The  crossing  (1972). of  study  in dendrites  o c c u r has  the s i g n i f i c a n c e  r e p r e s e n t t h e t e r m i n a l of  electron-lucent  terminals  protein  can  known.  i n :this  g r a i n s found  this  frequently as the symmetrical  t e r m i n a l s may  results  s o u r c e of t h e A c h E - p o s i t i v e p r e -  were i n n e r v e  synaptic  explain-  observed p r e t e r m i n a l  t e r m i n a l a x o n s i n t h e s u p r a g r a n u l a r l a y e r a r e not The  supra-  arguter-  terminal.  septum i s not h a l f  that  Yet in  - 45  the  m e d i a l septum; t h e r e f o r e  t h i s area  would h a v e t o  be  medial septal projection  the  to account f o r  seems u n r e a s o n a b l e s i n c e  from  the  the of  m e d i a l and the  the  septum and  lateral  planation n u c l e i and  one  another  these medially projection  and  from  the  observed no  to  segments  observed  (Raisman, e t a l . , 1965:  septal  Both  involved  in  ex-  medial  d i a g o n a l band n u c l e i . nuclei are  that  more l i k e l y  a r i s e s from the  the  projection  different  A  to  labelling.  & T a s s o n i observed  sections.  septal  septum  the  p r o f u s e as  h e n c e w o u l d n ' t be  terminal  situated  to the  Siegel  microscopic  i s that  septal projection  Raisman o b s e r v e d  septum p r o j e c t e d  hippocampal r e g i o n  same e l e c t r o n  lateral  more t h a n t w i c e a s  This  lateral  -  in  of  the  Shute &  Lewis,  1963). The c a n n o t be  possibility  ation after a  recorded  bria)  pathways a r i s e f r o m t h i s a r e a  sectioning  a dentate the  most m e d i a l  e l e m e n t s of  however w i t h t h e  the  fornix  pattern  deep t o  (dorsal  of  of  response to  fimbria.  s e p t a l pathway r u n n i n g  between t h e  nor  two  discounted; p a r t i c u l a r l y , i n view  Andersen s t i l l  is  that  He  This  studies.  that  stimul-  that  the v e n t r i c u l a r  there  surface  most l a t e r a l ( f i m d o e s not  l a b e l l i n g observed  w i t h Raisman's d e g e n e r a t i o n  fact  septal  concluded  f o r n i x ) and  system.  the  agree  in this  study,  - 46 -  Fifty  percent  onto d e n d r i t i c gyrus. sible  spines  i n the  granule  present  of  must be  of  the  basket  l a y e r , two  Below t h i s  into  molecular  the  means by  is a layer  which t h e  e x c i t e granule  would mean t h a t t h e monosynaptic. cribed than  by  the  The  Cajal  through  in this  to  dendrites  Although  the  onto axons)  Yet  Golgi  majority  contact  Immediately  f o u n d ; one  layer  A  type  (possibly inhib-  which sends i t s axons t o with  1911).  axons  to the  cells  they  cells,  granule  this  provide  gyrus  cells  have been  possess  the  ascending  These c e l l s  to the dentate  of t h e s e  of g r a n u l e  identify  the  zone. are  e l i m i n a t e them a s a p o s s i b l e p o s t s y n a p t i c research  zone.  excitatory interneurons.  s e p t a l input  (1911).  dendrites  (Cajal,  not  (some or  septal terminals  l a y e r of c e l l s  s e p t a l input  cells  portion  c e l l types  another  do  pos-  onto c e l l b o d i e s .  in the granular  c e l l s ) , and  alveus.  the  i s not  cells  z o n e , and  were not  i s that  dentate  s e p t a l synapses  the b a s i l a r  in this  c e l l types  axons t e r m i n a t i n g  itory  1911),  invading  observed  d e n d r i t e s of o t h e r  with  the g r a n u l e  o n t o some b a s i l a r  possibility  below the g r a n u l a r  z o n e of t h e  p o s t s y n a p t i c element Since  show d e n d r i t e s  synaptic contacts  more l i k e l y  the  (Cajal,  onto a p i c a l d e n d r i t e s not  s y n a p s e s made c o n t a c t s  subgranular  study.  dendrites  cells  s t a i n s do  a  i n the  Identification  have b a s i l a r  or  of t h e asymmetrical  fewer  could This i s not des-  spines  d o e s not n e c e s s a r i l y structure.  p o s t s y n a p t i c element  of t h i s  Further pathway  is indicated. The be  role  of t h e  a p p r e c i a t e d when a  s e p t a l input clear  to the  understanding  dentate of the  g y r u s can synaptic  only  - 47 -  organization clarifies layer  of t h i s  system  i s obtained.  The p r e s e n t  some o f t h e p r e v i o u s a m b i g u i t i e s a b o u t  of t h e dentate gyrus  the s e p t a l a f f e r e n t s  study  t o which p r o j e c t , but  r a i s e s q u e s t i o n s c o n c e r n i n g t h e p o s t s y n a p t i c element  involved.  The  micro-  visualization  scopy  indicates  cholinergic septal and is  o f t h e s e p t a l t e r m i n a l by e l e c t r o n  i t may h a v e s t r u c t u r a l  from  system  one f r o m  t h e d i a g o n a l band  needed b e f o r e t h e f u l l  limbic  t o known  nerve t e r m i n a l s but r a i s e s t h e p o s s i b i l i t y  terminals, possibly  another  similarities  the medial nucleus.  implications  function a r e understood.  septal  o f two nucleus  Further research  of these f i n d i n g s t o  - 48 -  BIBLIOGRAPHY  - 49 Andersen, P., B l a n d , B.H.,  & Dudar, J.D.  hippocampal o u t p u t .  O r g a n i z a t i o n of t h e  Exp. Bra i n R e s e a r c h 17; 152-168,  1973. Andersen, P., B r u l a n d , N.,  Kaada, B.  A c t i v a t i o n of the  d e n t a t e area by s e p t a l s t i m u l a t i o n , A c t a P h y s i o l o g i c a Scanda n a v i a , 51: 17-28, 1961. Andersen, P., H o l m q u i s t , B., and, V o o r h o e r v e , P.E.  Excitatory  synapses on hippocampal a p i c a l d e n d r i t e s a c t i v a t e d by e n t o r h i n a l s t i m u l a t i o n . Scanda n a v i a 66: 461-472, Andy, O.J., & Stephan, H.  1966.  The Septum of t h e C a t .  S p r i n g f i e l d , 111. Bachmann, L. & S a l p e t e r , M.M. microscope.  Acta P h y s i o l o g i c a  Thomas,  1964. Autoradiography with the e l e c t r o n  A quantitative evaluation.  Journa 1 C e l l  B i o l o g y 33: 229-305, 1965. B i s c o e , T.J. & Straughan,  D.W.  Micro-electrophoretic studies  of neurones i n t h e c a t hippocampus.  Journa1 of  P h y s i o l o g y 183: 341-359, 1966. B l a c k s t a d , T.W.  Commissural c o n n e c t i o n s of the hippocampal  r e g i o n i n t h e r a t , w i t h r e f e r e n c e t o t h e i r mode of t e r mination. B l a c k s t a d , T.w.  J our na1 Comparat i v e N e u r o l o g y 105: 417-537, 1956.  On t h e t e r m i n a t i o n of some a f f e r e n t s t o t h e  hippocampus  and f a s c i a d e n t a t a .  An e x p e r i m e n t a l s t u d y  i n t h e r a t . A c t a Anatomy 35: 202-214, 1958. B l a c k s t a d , T.W.,  Brink,  Hero, J . , Jeune, B.  D i s t r i b u t i o n of  hippocampal mossy f i b e r s i n t h e r a t . An e x p e r i m e n t a l study w i t h s i l v e r i m p r e g n a t i o n methods. Comparative N e u r o l o g y 138; 433-450, 1970.  Journa 1  B l a n d , B.H.,  K o s t o p o u l o s , G.K.  sensitivity Journal Bloom, F.  of  of  Physiology  (F.O.  B o d i a n , D.  An  In:  of  The  Schmitt,  pp.  Cajal,  S.  Ramon.  The  Analysis the  tration  J o u r na1  structure  i n the  the  second New  study  York:  of  controlled 44:  115-124,  Ammonshorn. 1968  1970.  Charles  (Translation  of  of  synthesis of  CM.,  dorsal and  and  transport  acetylcholinesterase  hippocampus a f t e r  adminis-  Bra i n Research  W o o l s l e y , T.A.  raphe n u c l e i  156:  Connections  i n the study.  179-206,  autoradiographic  in the  21-51,  1975.  An  Journa1  Price,  J.L.,  demonstration  c e n t r a l nervous  1972.  P e r s o n a l communication,  rat.  of  1974.  H e n d r i c k s o n , A.E.,  The  of a x o n a l c o n n e c t i o n s 37:  & P f a f f , D.W.  degeneration  G o t t l i e b , D.I.,  Research  G.S.  1974.  median and  Brain  Lynch,  diisopropylflurophosphate.  485-496,  Cowan, W.M.,  Kozan, M.D.,  septum and  Comparative Neurology  Cowan, W.M.  A  means o f  hippocampus: r e c o v e r y  autoradiographic  and  1974.  synaptic  C e l l Biology  of  Cotman, C.W.,  C o n r a d , L.C.A., L e o n a r d , the  of  characterization  of a c e t y l c h o l i n e s t e r a s e  rat  activity  81:  966-971,  edition).  Chippendale, T.J.,  in  Canadian  1970.  C. Thomas, S p r i n g f i e l d , I l l i n o i s , 1911  52:  function  v e s i c l e s by  aldehyde f i x a t i o n .  neurons.  editor-in-chief)  microscopic  synaptic  Acetylcholine  Neurosciences.  729-743,  electron  classes  & Pharmacology  s t r u c t u r e and  ultra structure.  Rockefeller  J.w.  hippocampal formation  Correlating  program.  & Phillis,  system.  - 51 C r o s b y , E.C.  The  Journal Daitz,  H.M.,  forebrain  Comparative  and fornix  and  Psychiatry  system.  & Koenig.  The  8 of Sympona  The  release Brain Eccles,  Fonnum, F.  of t h e c o n n e c t i o n s of  of N e u r o l o g y ,  Neurosurgery,  1954.  turnover of p r o t e i n s In:  1917.  i n a x o n s and  C e l l u l a r D y n a m i c s of t h e N e u r o n . V o l . Society  ed. Academic P r e s s ,  pp.  35-40,  from  the rabbit  Biology.  1969.  nuclei stimulation  83: 123-133,  on  the  hippocampus.  1975.  P h y s i o l o g y of Synapses.  T o p o g r a p h i c a l and  for Cell  B e r l i n : Springer,  subcellular  localization  and  Journal  of Neurochemistry  17: 1029-1037,  & Cowan, W.M.  the d i s t r i b u t i o n of a x o n a l  D.I.  minals containing vesicles and  Zeitschrift  G r a y , E.G.  S c i e n c e 157:  Axo-somatic  cerebral  cortex,  of Anatomy J.D.  of  d e n t a t e g y r u s of t h e r a t  axo-dendritic  and  electron  Journal  & McGeer, P.L.  infant r a t .  129  :  413-429, nerve  s y n a p s e s of  microscope  the  study.  Journa1  1959.  Hippocampal  electrical  activity  o f N e u r o p h y s i o l o g y 17: 533, Synaptogenesis  Experimenta1  1972.  1967.  and  A.A.  ter-  synaptic  by g o l d f i s h o p t i c  196-198,  region.  1970.  flattened  (London) 93: 420-433,  and A r d u i n i ,  in arousal. T.  and  Zellferschung  T r a n s p o r t of p r o t e i n  fibers.  Hattori,  spheroidal  i n t h e hippocampus and  cat.  Grafstein,  on  r a t hippocampal  1964.  of  choline acetyltransferase  Gottlieb,  Green,  Journa1  of a c e t y l c h o l i n e  The  325-402,  :  studies  e f f e c t of s e p t a l  Research  J.C.  27  Mississippiensis.  of the I n t e r n a t i o n a l  Barondes,  D u d a r , J.D.  Neurology  17: 75-82,  nerve e n d i n g s .  S.H.  of a l l i g a t o r  P o w e l l , T.P.S.  the  D r o z , B.  -  i n the corpus  Neurology  38:  70-79,  1954. striatum 1973.  - 52 Hattori, of  T. & McGeer,  P.L.  Electron  cholinesterase-containing  microscopic identification structures  i n t h e corpus  s t r i a t u m by d i i s o p r o p y l f l o u r o p h o s p h a t e u p t a k e . imental Neurology, H e n d r i c k s o n , A.  4 5 : 541-548, 1974.  Electron  transport.  Exper-  microscope d i s t r i b u t i o n  Journal  of Comparative  of axoplasmic  Neurology,  144: 381-  398, 1972. H e r t z , A . & N a c i m i e n t o , A.C. U b e r d i e werkung v o n Pharmaka a u f N e u r o n e d e s Hippocampus noch Verabfalgung. 251:  mikrollektophoretischer  A r c h . Exp. P a t h a l o g i s c h e u Pharmalogische,  295-314, 1 9 6 5 .  Hjorth-Simonsen,  A.  Projection  e n t o r h i n a l area  of the l a t e r a l  t o t h e hippocampus and f a s c i a  Journal Comparative Neurology Hjorth-Simonsen,  A.  part  Some i n t r i n s i c  Hjorth-Simonsen,  Neurology  c o n n e c t i o n s of t h e h i p p o -  perforant  impregnation. K a t z , B. N e r v e , New Y o r k ,  path i n the r a t s t u d i e d  and S y n a p s e .  R.A.  McGraw H i l l  by  of t h e  silver  144: 215-232,1972.  Book Co.,  T h e Rat B r a i n : A  stereotaxic  T h e W i l l i a m s & W i l k i n s Co., B a l t i m o r e ; 1963.  L a a t s c h , R.H. & Cowan, W.M.  Electron  t h e d e n t a t e g y r u s of r a t I . Neurology Lewis,  O r i g i n and t e r m i n a t i o n  1966.  K o n i g , J.F.R. & K l i p p e l , Atlas.  B.  Journa1 Comparative Neurology  Muscle,  J o u r na 1  147: 145-162, 1973.  A. a n d J e u n e ,  hippocampal  dentata.  146: 219-232, 1972.  campus i n t h e r a t : a n e x p e r i m e n t a l a n a l y s i s . Comparative  of the  m i c r o s c o p e s t u d i e s of  Journa1  of Comparative  1 2 8 : 359-396, 1966.  P.R., S h u t e , C C D . , & S i l v e r , A . C o n f i r m a t i o n from c h o l i n e a c e t y l a s e a n a l y s i s of a massive c h o l i n e r g i c i n n e r v a t i o n of t h e hippocampus. J o u r n a l of P h y s i o l o g y  (London)  172:  L o r e n t o de No,  R.  Cortex.  1-10,  1964.  S t u d i e s on t h e s t r u c t u r e  J o u r n a l f u r p s y c h o l o g i e and  381-438,  wada, J.A.,  T e r a o , A. and  synthesis  in various brain  lesions.  E x p . N e u r a l . 24: 277-284,  & Halaris,  neurons  A.E.  Jung, E .  Hippocampal  L y n c h , G.  164:  G.D.  R a v e n : New R a i s m a n , G.,  York,  innervation  The  The  serotonin  J o u r na 1  distribution  163-174,  of  septal  J o u r n a l of  1973.  S t r u c t u r e and  Function  & P o w e l l , T.P.S.  The  c o m m i s s u r a l , and a s s o c i a t i o n  hippocampus.  by  of  Synapses.  1972.  Cowan, W.M.,  afferent,  R a i s m a n , G.  152:  & P u r p u r a , D.P.  septal  171-184,1975.  & Cotman, C.  Comparative Neurology,  Amine  1969.  p r o j e c t i o n s t o t h e hippocampus i n r a t .  Pappas,  45:  r e g i o n s w i t h caudate or  of the m i d b r a i n raphe i n t h e r a t .  Comparative Neurology Mosko, S.,  neurologie.  1933.  McGeer, E.G.,  Moore, R.Y.  of the C e r e b r a l  B r a i n 88:  963-996,  extrinsic  fibers  of the  1965.  C o n n e c t i o n s o f t h e Septum.  B r a i n 89:  317-348,  1966. Robertson,  J.D.  Sciences. in-chief). R o g e r s , A.W. lishing Segal,  M. rat  U l t r a s t r u c t u r e of Synapses. A Second New  Study P r o g r a m .  York: Rockefeller,  & Landis,  New S.  York:  The  Neuro-  (F.O. S c h m i t t , pp.  T e c h n i q u e s of A u t o r a d i o g r a p h y . Co.  In:  715-728, Elsevier  editor-  1970. Pub-  1967.  A f f e r e n t s t o t h e h i p p o c a m p u s of t h e  s t u d i e s w i t h t h e method o f r e t r o g r a d e t r a n s p o r t  horseradish peroxidase.  Brain Research,  78: 1-15,  of 1974.  -  S h e p h e r d , G.M.  The  Shute, C C D .  Oxford  University  and  Lewis,  P.R.  the B r a i n  P r e s s , New  The.use of  nervous pathways i n the ( B a s e l ) 2:  34-49,  S h u t e , C.C.D. & L e w i s , the  of  -  York,  An London,  1974.  t e c h n i q u e s combined w i t h  of  -  Synaptic Organization  Introduction. Toronto:  54  brain  of  operative brain.  cholinesterase p r o c e d u r e s to  Bibliotheca  follow  Anatomica  1961.  P.R. the  Cholinesterase-containing rat.  Nature  systems  (London) 199:  1160-1164,  1963. Shute, C C D .  & L e w i s , P.R.  terminals in  the  69: Siegal,  and  J.P.  f r o m t h e v e n t r a l and  Smith, CM.  The  campus. c.  Stefanis,  the  dorsal  Evolution  release  British  F.A.  185-200,  of a c e t y l c h o l i n e  6:  171,  on  of  the  lateral geniculate 173-180,  neurons  Zellforschung.  1968.  projections the  cat.  Bra i n  1971. from r a b b i t  J o u r na 1 P h a r m a c o l o g y 4 5 :  Influence  acetylcholine  303:  4;  efferent  hippocampus of  Hippocampal neurons: t h e i r  Pharmacologist  cholinergic  containing  Zeitschrift  Differential  microelectrophoretically  Steiner,  rat.  of  1966.  & Tassoni,  B e h a v i o u r and  microscopy  acetylcholinesterase  hippocampus of  334-343,  A.  Electron  hippo-  172P,  1972.  responsiveness  administered  to  endogenous a m i n e s .  1964. microelectrophoretically r e s p o n s i v e n e s s of  neurons.  Pflugers  applied  hippocampal A r c h . Ges.  and  Physiol,  - 55 -  StDrm-Mathison,  J.  Q u a n t i t a t i v e h i s t o c h e m i s t r y of a c e t y l -  c h o l i n e s t e r a s e i n the r a t hippocampal to h i s t o c h e m i c a 1 s t a i n i n g .  region  correlated  Journa1 of Neurochemistry,  17: 739-750, 1970. Storm-Mathison,  J.  Glutamate decarboxylase i n the r a t hippo-  campal r e g i o n a f t e r l e s i o n s of the a f f e r e n t f i b e r Evidence that t h e enzyme i s l o c a t e d i n i n t r i n s i c  systems. neurons.  B r a i n Research 40: 215-235, 1972. T i s d a l e , A.D. & Naka jima, Y.  F i n e s t r u c t u r e of s y n a p t i c v e s i c l e s  i n two types of nerve t e r m i n a l s i n c r a y f i s h r e c e p t o r organs:  stretch  Influence of f i x a t i o n methods.  Journa1  Comparative Neurology 165: 369-386, 1976. Young, M.W.  The n u c l e a r p a t t e r n and f i b e r connections of the  n o n - c o r t i c a l c e n t e r s of the t e l e n c e p h a l o n of t h e r a b b i t (Lepus c u n i c u l u s ) .  Journa1 Compa rat i v e Neurology 65:  295-401, 1936. Zimmer, J .  I p s i l a t e r a l a f f e r e n t s t o t h e commissural zone of  the f a s c i a by s i l v e r  dentata, demonstrated impregnation.  142: 393-416, 1971.  i n decommisurated  rats  Journa 1 Comparative Neurology  - 56  - 57 -  Figure  2a  Horizontal  s e c t i o n showing  u s e d f o r g r a i n c o u n t s of Figure  grains  autoradiography.  i n the The  o f one  animal  region.  f i m b r i a shown by  lateral ventrical  light  i s to the  microscopic lower  right.  2c  Distribution (PL), g r a n u l a r dentate  hippocampal  site  2b  Silver  Figure  the  injection  gyrus.  of  layer  silver (GL)  grains  and  i n the  molecular  polymorphic  layer  (ML)  of  layer the  - 57a  -  - 58  -  Figure 3 G r a i n counts i n the hippocampal r e g i o n s C A l , CA3, CA4 the dentate gyrus.  Counts were done i n the supra  l a y e r , stratum radiatum oriens  ( S t . O.),  molecular l a y e r layer  (PL).  ( S t . R.)  and  subpyramidal  cortex  pyramidal layer,  stratum  the three l a y e r s of the dentate gyrus: the (ML), g r a n u l a r l a y e r  (GL), and  polymorphic  The polymorphic area of the dentate and area  of the hippocampus are counted as one a r e a . ing was  seen i n the caudate (A.E.).  and  nucleus  (CN), and  Background  CA4  labell-  the e n t o r h i n a l  - 58a -  st.  AE  0 C A l  st.R  st.  0 C  st. R A  3  ML  G L C A  4  D  G  - 59 -  F i g u r e 4a Tip of  o f m e d i a l wing  silver grains.  o f d e n t a t e g y r u s showing  S u b g r a n u l a r z o n e i s on t h e l e f t  ecular  l a y e r on t h e r i g h t .  Figure  4b  Silver ground  grains  distribution  i n Entorhinal cortex  and  (A.E.) t o show  mol-  back-  labelling.  Figure 5 Ultrastructure Insert  o f s u b g r a n u l a r zone of t h e d e n t a t e  shows a s y n a p s e en p a s s a g e .  gyrus.  -  5 9 a  -  - 60 -  Figure  6a  Asymmetrical  synapse  onto a d e n d r i t e  i n the dentate  synapse  i n the dentate gyrus  gyrus. Figure  6b  Asymmetrical  n e r v e t e r m i n a l wrapped a r o u n d  Figure  a  spine.  6c  Symmetrical Arrow  a  showing  indicates  synapse  onto d e n d r i t e  symmetrical  thickening.  i n the dentate gyrus.  - 60a -  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0093708/manifest

Comment

Related Items