"Science, Faculty of"@en . "Zoology, Department of"@en . "DSpace"@en . "UBCV"@en . "Lazareff, Anne Eileen"@en . "2012-03-08T17:35:37Z"@en . "1949"@en . "Master of Arts - MA"@en . "University of British Columbia"@en . "A histological investigation was carried out on the esophagus and stomach of the following birds: kingfisher (Megacercyle alcyon caurina), California murre (Uria aalgae Californioa), screeoh owl (Otus asio kennicotti),Peale's faloon (Falco peregrinius pealei), and sparrow hawk (Falco sparverius sparverius). A number of stains was used to intensify the different structures present. \r\nIn the kingfisher, murre and owl the esophagus was a thin walled highly expansible tube of generally even calibre, whereas in the Peak's falcon the anterior part was dilated into a sac. The wall of the esophagus possessed the usual structure characteristic of this region of the digestive tube. Three types of glands have been distinguished in these birds. In the kingfisher and owl simple oval glands were situated almost entirely within the epithelium. The glands and excretory duct were composed of similar cells with slight variations occuring in excretory duct lengths. In the California murre the glands were still simple but had sunken to the tunica propria with just the excretory ducts passing through the epithelium. The gland cells were narrower, and the duct cells resembled those observed in the owl and the kingfisher. These glands were all apocrine secretory. However, in the Peale\u00E2\u0080\u0099s falcon and sparrow hawk secretion was holocrine. These glands were deeply embedded within the tunica propria and resembled the esophageal glands of the chicken. The excretory ducts were lined by squamous epithial cells. Although the birds examined possessed a variety of food habits: fish, mammals, birds and crustaceans, the food was essentially meat. However, considerable variations in the structure of the esophagus were observed.\r\nThe proventriculus was comprised of: a mucosa, indented with minute gastric pits, a muscularis externa of three layers of smooth muscle, and a lamina adventitia that surrounded the entire tube. Within the mucosa the deep glands were situated. These were composed of large lobes, enveloped in a dense capsule of connective tissue and internally consisted of simple tubules that radiated about a central excretory duct. The structure of the proventriculus was more or less uniform in the birds investigated, with only slight variations occuring in cellular arrangement and cellular size.\r\nThe gizzards in the birds examined were large spherical structures that filled a majority of the abdominal cavity. In the kingfisher, owl, Peale's falcon, and sparrow hawk, the gizzard was lined by a thin keratinoid lining that was secreted by the glands present in the gizzard mucosa. The muscularis externa was of approximately equal thickness throughout. In the murre, the keratinoid layer was five or six times as thick as in the above birds and the muscles showed a heavy development on the dorsal and ventral sides. This development took place toward a grinding mechanism that was necessary for processing the hard shelled crustaceans eaten by this bird."@en . "https://circle.library.ubc.ca/rest/handle/2429/41242?expand=metadata"@en . "THE COMPARATIVE HISTOLOGY OP THE ESOPHAGUS AND STOMACH OP BIRDS OF DIFFERENT FOOD HABITS - - by ~ Anne Eileen Lazareff A Thesis submitted in partial fulfilment of the requirements for the degree of MASTER OF ARTS In the Department of Z O O L O G Y The University of British Columbia Ap r i l , 1949 - i i i -ABSTRACT A histological investigation was carried out on the esophagus and stanaoh of the following birds: kingfisher (Msgaoeroyle aloyon oaurina). Balifornia murre(Uria aalgae oalifornioa), soreeoh owl (Otus asio kennioottiJ^Peale's faloon (Faloo perigrinius pealei). and sparrow hawk (Faloo sparverius sparverius)* A number of stains T S \u00C2\u00AB 0 S used to intensify the different structures present. In the kingfisher, murre and owl the esophagus was a thin walled highly expansible tube of generally even calibre, whereas in the Peak's faloon the anterior part was dilated into orsao*\" The wall of the esophagys possessed the usual struoture characteristic of this region of the digestive tube* Three types of glands have been distinguished i n these birds. In the kingfisher and owl simple oval glands were situated almost entirely within the epithelium. The glands and excretory duct were composed of similar c e l l s with slight variations ooouring in excre-tory duot lengths. In the California murre the glands were s t i l l simple but had sunken to the tunica propria with just the excretory duots passing through the epithelium. The gland oells were narrower, and the duct c e l l s resembled those observed in the owl and the kingfisher. These glands were a l l apocrine secretory. However, in the Peale*s faloorjand sparrow hawk secretion was holocrine. These glands were deeply embedded within the tunica propria and resembled the esophageal glands of the chicken. The excretory duotsirere lined by squamous epithial c e l l s * Although the birds examined possessed a variety of food habits* f i s h , mammals, birds and crustaceans) the food was essentially meat. However, - I V considerable variations in the structure of the esophagus were observed* The proventrioulus was comprised oft a mucosa, indented with minute gastric pits* a musoularis externa of three layers of smooth muscle, and a lamina adventitia that surrounded the entire tube* Within the mucosa the deep glands were situated. These were oomposed of large lobes,Aenveloped in a dense capsule of connective tissue and internally oonsisted of simple tubules that radiated about a oentral excretory duct* The structure of the proventrioulus was more or less uniform in the birds investigated, with only slight variations ooouring in cellular arrangement and cellular size* The gizzards in the birds examined were large spherical structures that f i l l e d a majority of the abdominal oavity* In the kingfisher, owl, Peale's falcon, and sparrow hawk, thee gizzard was lined by a thin keratinoid lining that was secreted by the glands present in the gizzard mucosa* The musoularis externa was of approximately equal thiokness throughout* In the murre, the keratinoid layer was five or six times as thiok as in the above birds and the muscles showed a heavy development on the dorsal and ventral sides* This development took plaoe toward a grinding mechanism that mis necessary for processing the hard shelled orustaoeans eaten by this bird* TABLE OP CONTENTS Table of Contents\u00E2\u0080\u0094 \u00E2\u0080\u0094 - \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 i . A b s t r a o t - \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 - \u00E2\u0080\u0094 \u00E2\u0080\u0094 - \u00E2\u0080\u0094 \u00E2\u0080\u0094 - \u00E2\u0080\u0094 \u00E2\u0080\u0094 i i L Introduction\u00E2\u0080\u0094 \u00E2\u0080\u0094 - \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 iv. Acknowledgement s\u00C2\u00AB*\u00C2\u00BB\u00C2\u00BB\u00C2\u00BB \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 v i . Historical R e v i e w \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 - I , Materials and Methods \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 O b s e r v a t i o n s \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 1 2 Esophagus Kingfisher (jfegaoeroyle aloyon oaurina)\u00E2\u0080\u0094-12. California murre(Uria aalgae c a l i f o r n l o a } \u00E2\u0080\u0094 *5-Soreech owl (Otus aslo k e n n l o o t t l ) \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00C2\u00BB \u00E2\u0080\u0094 f Short-eared owl (Aslo flammeus flammeus)\u00E2\u0080\u0094 \u00E2\u0080\u0094 Peale's falcon (Palop perigrinius p e a l e i ) \u00E2\u0080\u0094 Sparrow hawk (Faloo sparverius sparverius)\u00E2\u0080\u0094 Pigeon hawk (Faloo oolumbarius sucklgyi) Proventrioulus Kingfisher (jfegaoeroyle aloyon o a u r i n a ) \u00E2\u0080\u0094 \u00C2\u00BB 2 2. California murre (Uria aalgae californioa)-- 24. Soreeoh owl(jQ\u00C2\u00B1us asio k e n n i o o t t i ) - \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 25. Short-eared owl(Asio flammeus flammeus) Peale's faloon(Faloo per&grinus p a & l f l i ) \u00E2\u0080\u0094 \u00E2\u0080\u0094 27. - i i -Sparrow hawk(Faloo sparverius sparverius) Pigeon hawk (Faloo oolumbarius suokleyi) Gizzard Kingfisher (Megaoeroyle aloyon oaurina^\u00E2\u0080\u0094\u00E2\u0080\u0094\u00C2\u00BB2Q^ California murre (Uria aalgae o a l i f o r n i o a ) - 3 l K Soreeoh owl (Otus asio kenniootti) \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 32. Peale's faloon (Faloo pertgrinius pealei)-- \"3 4.. Sparrow hawk (Faloo sparverius sparverius) Pigeon hawk (Faloo oolumbarius suokleyi) Conolusions and S u m m a r y \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 Literature C i t e d \u00E2\u0080\u0094 \u00E2\u0080\u0094 4f. P l a t e s \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u00A2 \u00E2\u0080\u0094 4 7 INTRODUCTION Although aotive investigations of the alimentary tract in birds have been carried out for nearly two oenturies our knowledge of this organ system s t i l l remains inadequate. The work of such men as Reaumur (1752) who concerned himself with the triturant action of the gizzard on introduced substances, Hunter (1786) who studied muscle move-ment and noises of stones in the gizzard, Cuvier (1805), Home (1814) and H. Milne Edwards (1857-1881) illustrates the early beginnings of Inquiry into the mechanisms of the digestive tract. It was not u n t i l the work of Molin (1853) that the f i r s t methods of histological teohnique were introduced and investigations turned more to the finer structures of the organs. Among the earlier workers who engaged themselves i n microana\u00E2\u0080\u0094 tomical investigations were Berlin (1852), Leydig (1857), Flower (i860), Bergmann (1862), Hasse (1865),~ Curshman (1866), Wledersheim (1871), Gar-rod (1872) and Klein (1881). Even with their imperfect methods these men have made some advances to which only further knowledge can be added by continuous investigation and refinement i n apparatus and technique. It is the authorfa intention, in the study here presented, to add to accumulating knowledge concerning the alimentary tract of the birds. For this investigation, two groups of birds have been ohosenj one ohiefly a piscivorus group and the other a carnivorous one. To rep-resent the fish-eaters the western belted kingfisher (Megacerovle alcyon oaurina Grinnell) and the California murre (Uria aalgae. californica Bryant) were studied. The kingfisher is almost entirely a fish-eater while the California murre can exist equally well on f i s h or crustaceans -vt-(Taverner 1947). Of the carnivorous species chosen, the screech owl (Otus asio kennicotti E l l i o t ) and the short-eared owl (Asio flammeus flammeus Pontoppidan) show preference for a diet consisting mainly of small mam-mals, while the Peale*s falcon (Faloo peregrinius pealei Ridgeway) and the black pigeon hawk (Faloo columbarius suckleyi Ridgeway) are examples of the few birds that prefer birds as food. (Taverner 1947, May 1935, Barcus 1930)8 The sparrow hawk (Balco sparverius aparverius Ridgeway) although i t belongs to the same genus as the Peale's falcon and pigeon hawk subsists contrary to the implications of i t s name, chiefly on i n -sects and only occasionally oaptures a bird (Taverner 1947, May 1935). In presenting this work, a comparative description w i l l be given f i r s t of the anatomy and histology of the esophagus and stomaoh of each speoies followed by an attempt to correlate the histological structure of the tract with the food habits of that species. - v i i -ACKNOWLED GEMENTS The writer i s indebted to Dr. W. A. Clemens and the members of the s t a f f of the Department of Zoology, University of B r i t i s h Columbia for granting permission to carry out t h i s investigation, especially to Professor G. J . Spencer for suggesting the problem and to Dr. I. MoT. Cowan for the kindly interest that he has shown. The author wishes to express her sincere appreciation f o r the helpful o r i t i o i s m and suggestions that Dr. J. A.CNicol has given i n the preparation of t h i s paper. Grateful appreciation i s extended tot Dr. I . MoT. Cowan, Dr. and Mrs. E. Black, Mr. F. L. Beebe, Mr. C. Guiget, Mr. P. Martin, Mr. C. Law and Mr. E. Samann for the c o l l e c t i o n of material used i n t h i s work; to Miss Anne M. Smith for obtaining many i n t e r l i b r a r y loans); to Miss Joan Hannay for typing t h i s t h e s i s j to Mr. R\u00C2\u00BB S\u00C2\u00BBteiner for his help i n photomicrogrophyj and f i n a l l y to Miss Vivian V e r r a l l , to my s i s t e r , E l s i e and to my fellow students for t h e i r co-operation at a l l times. THE COMPARATIVE HISTOLOGY OF THE ESOPHAGUS AND STOMACH OF BIRDS OF DIFFERENT FOOD HABITS HISTORICAL REVIEW Several authors have described b r i e f l y the general anatomy of the esophagus and stomaoh of birds, but very few have touched upon the histology of these regions other than those of the domestio fowl. Kingsley ( 1926) and Scheer (1948) i n describing the anatomy, of the digestive t r a c t of the bird spoke of the esophagus as an elon-gated tube with complex diverticulae. Kingsley( 1926) stated that i t was usual for the esophagus to be of uniform diameter but frequently i n birds marked d i l i t a t i o n s were present. Wiedersheim and Parker ( 1907) expressed the opinion that modifications of the esophagus occurred as adaptations a r i s i n g from food habits, the mode of l i f e and the absence of teeth i n birds. These workers found that i n gramnivorous birds and i n birds of prey either the whole gullet formed an expanded sac or a ventral outgrowth was present. This d i l a t a t i o n or outgrowth they referred to as the crop or ingluvies. Beddard (1898) stated that gallenacious birds were provided with a crop while other birds possessed a slight,permanent or temporary d i l a t a t i o n that forshadowed the f u l l y developed orop. Of the l i t e r a t u r e pertaining to the histology of the avian esophagus and crop, the majority deals with the domestic fowl. Very l i t t l e has been written about the histology of these structures i n other birds. Barthels (1895) desoribed b r i e f l y the histology of the - 2 -v\u00C2\u00A9d\u00C2\u00A3=%he esophagus of a number of birds, among which he mentioned --Uria lean via ( a murre) and fltus brachyotus ( the barn owl). Kaden ( 1932) on the other hand confined her work to a study of only the epithelium, glands and modes of secretion of these glands for a large group of birds. For the murre ( Uria lorn via) Barthels ( 1895) stated that - the esophagus was thrown into about twelve folds which disappeared at the proventrioulus. The epithelium was thick and consisted of small c e l l s . The glands were small with long sharp Hacks extending through the epithelium. The muscle layer consisted of an external cir o u l a r muscle .twSefcitaes as thick as the internal longtitudinal muscle layer. Both of the above mentioned authors have worked on various species of the Family Strigidae ( the owls). The esophageal w a l l of Gtus brachyotus ( the barn owl) was described by Barthels ( 1895) as highly folded and possessing a weakly developed mucosa. The e p i t h e l i a l c e l l was f i l l e d by a globular and s l i g h t l y flattened nucleus. Kaden (1932) i n d i s -cussing the epithelium of Asio otus stated that i t oonsisted of f l a t \" o e lls with oval nu c l e i . The epithelium was thin and did not vary i n thickness throughout the whole length of the esophagus. Barthels described the esophageal glands as oval structures lined with cuboidal e p i t h e l -ium and possessing short excretory ducts. Kaden stated that these glands were round or oval with their form and size remaining the same throughout the esophagus. The gland c e l l secretion was transparent and granular and stained with muci-carmine. The glands excreted d i r e c t l y into the lumen. Borthels ( 1895) stated that the la&ina propria was made up of fibrous connective tissue with numerous round n u c l e i . Kaden (1932) said that i t hardly existed. The musoularis externa was described by Barthels (1895) as a f a i n t l y homogeneous layer consisting of an inner longtitudinal and a very w e l l developed outer o i r c u l a r musole layer. Many blood vessels were persent i n the adventitia. Kaden (1936) also described the structure of the epithelium and glands found i n Faloo tinnuncuius ( the tower falcon) The epitheliuoa in this species was cornified and possessed a t y p i c a l stratum lucidum i n the region of the crop. The c e l l s were large and very clear with round nu c l e i . The stratum lucidum disappeared gradually i n the thoracic region but remained i n the sinuses of the folds while the remaining epitheluim showed strong continuous f l a t t e n i n g . Complicated folded holocrine glands were present i n this species. The folds were narrow and the c y l i n d r i c a l epitheluim of the gland was so high that the lumen of the gland consisted only of thin branching tubes. The c e l l s of the exoretory ducts were f l a t squamous c e l l s resembling the e p i t h i l i a l c e l l s . The stomach i s divided i n t e r n a l l y into two regions. The an-t e r i o r part Cazin (1886V.) Beddard (1898) Wiedershfeim and Parker (1907) and Kingsley (1926) called the proventricuius because of i t s glandular development and the posterior, the muscular gizzard. Scheer (1948) on the other hand referred to the anterior section as the musuclar gizzard and the posterior as the proventriculus. Cazin (1886) found i n a number of birds of prey and i n certain f i s h eaters that the proventriculus showed great development, i t s walls were extensible and i t s volume exceeded that of the gizzard. .Often there was no d i v i s i o n between the glandular portion and that of the gizzard. In the hawk the stomaoh consisted of a pocket which dilat e d at the i n f e r i o r terminal portion into what Cazin called a \"cul-de-sac\". Beddard (1898) also found that the proventriculus was not always separated from the gizzard. In 1887 -4-Cazin made a study of the histology of the stomach of some birds and for water birds and for birds of prey ( s i c ) he described the proventrioulus as a glandular area with each compound gland formed by an agglomeration of tubules i n a bl i n d sac of connective tissue. Each gland possessed two types of c e l l s that never mixed within a single tube. The granular enzyme c e l l s were always l o c a l i z e d i n the tubules at the periphery of the gland while the mucous c e l l s existed i n the oentral cavity and i n the c o l l e c t i n g canals that received the products of seoretion of the enzymatio c e l l s . Bergmann (1862) distinguished between three types of proventricular glands. The f i r s t he described as those i n which the gland tubes opened d i r e c t l y into a central oavity; the seoond i n which the gland tubules entered a central cavity byway of secondary canals and a t h i r d , i n which a number of l i t t l e canals opened into the oavity of the stomaoh, one beside the other. In 1888 Cazin described the mucosa of the proventrioulus as consisting of f i n e outpushings, separated by deep ridges formed by the f o l d i n g of the mucosa . Generally these folds were continuations of the esophageal furrows that passed to the gizzard. Wiedersheim and Parker JC1907) stated that the glandular stomach alone took part i n dissolving the food and Scheer (1948) compared the proventrioulus to the stomach of other vertebrates. The second part of the stomach, the gizzard has attracted investigators for a long time. Indeed,as far back as 1752 observations have been carried out on the gizzard. A l l authors agreed that the gizzard had a mechanical function. Wiedershe8: Plate XXXIII f i g . 59)* The soft velvety lining of the proventriculus i s soon replaced by the hard keratinoid lining of the gizzard. A single layer -30-of long simple tubular glands (Plate XXXIV, f i g * 60 a) secretes the lining* The glands are present i n the lamina propria and they connect with the pits of the gastric muscoa. Lining the crypts of the glands are low columnar or cuboidal c e l l s (Plate XXXIV f i g * 60 b), providdd with basal nuclei and granular cytoplasm* From these c e l l s the kez\u00E2\u0080\u0094 atijioid secretion of the gizzard i s poured into the lumen of the gland (Plate XIDdV, f i g . 60 c ) . As the secretion reaches the surface i t joins with that of the adjoining glands to form the hard continuous layer and presents striations representing the contributions of each glandular lumen* Within this layer BO me c e l l u l a r debris can be ob-served* The lamina propria (Plate XXXIV f i g * 60 d) surrounds the glands of the gizzard and only extends far enough to connect with the band of smooth longitudinal and circular muscle, or muscularis mucosa (Plate XXXIV, f i g * 60 e), or immediately below the glands. A submucosa of appreciable size joins the mucosa to the muscularis externa* The muscularis externa i s a thicker layer than that observed i n the esophagus or proventriculus. A heavy inner smooth longitudinal layer that extends into the folds present i n the gizzard composes a part of the muscularis externa. The circular muscle band i s increased considerably and each bundle i s surrounded by a connective tissue of collagen and elastic fibres. The entire gizzard wall i s abundantly supplied with blood Vessels. Present within the muscle bundle (Plate XXXV, f i g * 61 a) close to the serosa, are large bundles of nerve fibres dispersed at intervals throughout the circumferance of the gizzard* Fat,blood vessels, and muscle bundles enclosing more nerve fibres compose the tunica adventitea. A mesothelium surrounds the tube. California triurre - (Uria aalgae californica) The proventriculus enters the gizzard which continues for a short distance as a tube, before expanding into the bulbous structure of the gizzard. In this species muscular development (Plate XXXVI, f i g . 62, 63) is quite marked with greatest increase in muscular thick-ness occurring on the dorsal and ventral sides. Between these two regions extends the narrow lumen of the gizzard. Beginning at the proventriculus and continuing around the cavity of the gizzard, the muscles become very thin on the lateral sides (Plate XXXVI, f i g . 63) Beside the entrance of the proventriculus into the gizzard, the exit of the duodenum is situated. & sphincter (Plate XXXI fi g * 55) consisting of a band of muscle surrounds the duodenal exit. At the right a slight bulging of the gizzard wall takes place. The keratinoid lining i s thinner and greatly wrinkled. This may be the pyloric pocket that \"Cazin (I887) has described for some water birds. ' A mucosa, muscularis externa and a serosa make up the structure of the,,wall (Plate XXXVII, f i g . 6k)* A similar type of long simple tubular gland as observed in the kingfisher is present in this bifd. The glands possess essentially the same structure and appear to be of approximately the same size as those found in the kingfisher, but the keratinoid lining i s about five or six times as thick (Plate XXXVII, f i g . 6k a). -32-A simple cuboidal epithelium (Plate XXXVIII, f i g . 65 b) covers the cyrpts of the gizzard glands. The cells possess large spherical nuclei and a granular cytoplasm. Surrounding the glands is a much reduced tunica propria which joins almost immediately a layer of smooth circular and longitudinal muscle bundles. Small blood vessels are present in the tunica at the bases of the glands, A complete layer of submucosa surrounding the tunica propria i s not present. Instead, the tunica propria appears to intermingle with the muscle bundles, especially in the ridges that form the plicaa of the gizzard. The fibroblasts of the tunica propria and submucosa are more abundant and not as compressed as those observed in the other part os this digestive tract. The muscularis externa is greatly increased in some daces, particularly where folds (Plate XZXVTI, f i g , 6k d) of the gizzard wall are present. At these points the smooth muscle bundle s extend into the ridges to the submucosa. The inner longitudinal muscle is of various thicknesses, while the outer circular layer is quite regular. Between the muscle bundles, blood vessels pass in the connective tissue sur-rounding these bundles, A serosa encloses the entire gizzard. Screech Owl - (Otus asio kennicotti) After its junction with the proventriculus (Plate II, f i g , 2 i ) the gizzard in the owl passes into the abdominal cavity and f i l l s the left side almost completely. From tte right anterior region the duod-enum leaves to join the remainder of the intestine which f i l l s the right side. -33-The thickndss of the giazard wall in this species varies to some ex-tent. A thin layer of keratin lines the ental surface of the gizzard, the muscularis externa at some points is reduced (Plate XXXIX, f i g . 66 d) and a Iyer of fat envelops the exterior surface. The duodenal exit is slightly posterior to the entrance of the proventriculus. A sphincter (Plate XXXI, f i g . 55) consisting of a mere puckering of that region guards the exit of the duodenum. The wall is composed of essentially three coats, a mucosa, muscularis externa and a tunica adventitia (Plate XXXIX, fig * 6 6 ) . The proventricular glands end abruptly. The epithelium (Plate XL, Fig. 67 a) continues for a short distance and gradualy changes to the epithelium of the gizzard (Plate XLI, f i g . 68 a). The simple tubular gizzard glands with slightly bulbous basal regions are\u00E2\u0080\u00A2arranged side by side in the lamina propria. These glands join to the pits in the mucosa and through this neck region they sec-rete into the lumen of the gizzard. The cells of the glandular crypts are the usual cuboidal or low columnar epithelium, with spherical nuclei, whereas the cells of the neck and apical regions of the mucosal folds are of the t a l l columnar type. The glandular cytoplasm is granulated. Also present within these cells are large' colorless spheres, observed especially above and below the nucleus in the apical columnar cells, (Plate XLI, fig* 68 f ) . The tunica propria composed of dense collagenous tissue and abundantly supplied with fibroblasts, unites with the muscularis externa. A submucosa i s absent. The muscularis externa consists of an inner longitudinal smooth muscle layer and an outer circular muscle area which i s greatly thickened at various points (Plate XXXIX, f i g . 66 d). Nerve fibres occur frequently within'.the gizzard $uscle and ganglia are present in the tunica adventitia. The tunica adventitia oomposed-of collagenous fibres and far surrounds the entire tube. Peale's falcon (Falco peregrinius pealei) Sparrow Hawk (Falco sparverius sparvarius) Pigeon Hawk (F alco columbarius suckleyi) ' The gizzards of the Peale's falcon, sparrow hawk and pigeon hawk are more spherical in shape than those observed in the other birds. (Plate III figs. 6 , 7 , 8 ) . The proventriculus enters the gizzard from the posterior side. Beside this entrance and to the left is the exit of the duodenum. In the Peale's falcon a sphincter (Plate XXXJ, f i g . 57) , comppsed of two bulbous structures on one side and a fold of the wall on the other side, guards the opening to the duodenum. The muscular wall is reduced to a minimum, and the soft lining of the proventriculus is rapidly replaced by the keratinoid lining of the gizzard. Three coats contribute to the structure of the gizzard wall| a mucosa, muscularis externa and a tunica adventitia, (Plate XLII, f i g . 6 9 ) . The proventricular glands are soon replaced by the simple tubular glands of the gizzard which join the surface gastric pits. The surface pits are covered by simple t a l l columnar cells, whose cyto-plasm is distinctly divided into an apical pale, granular, cup-like -35-region, and a basal heavily granulated area, slightly above and below the nucleus, (Plate XLIII, f i g . 70 c). Surrounding the glands is a loose collagenous and reticular area and enclosing small groups of glands is a dense band of connective tissue (Plate XLII, fig* 6\u00C2\u00B0 d) beneath which lies the submucosa. Essentially the same structure as in the falcon is observed in the sparrow hawk. The glands are grouped by a dense connective tissue band, but not in as pronounced a manner as in the'peale's falcon, (Plate XLIV, f i g . 71 d). In the pigeon hawk the connective tissue band is not observed. The glandular cells are low cuboidal cells lining the crypt of the gland in a single row (Plate XLV, f i g . 72 b). The muscularis externa is greatly reduced in the falcon, whereas in the sparrow hawk and th? pigeon hawk i t is quite large. In the sparrow hawk i t is composed mainly of a long-itudinal band of muscle (Plate XLIV, f i g . 71 e) a i j w h v s j f e . .s are thrown into heavy plicae. Penetrating the muscle are many blood vessels and nerves. The serosa is thick and contains larger blood vessels and nerve fibres. CONCLUSIONS AND SUMMARY In the kingfisher, California murre, screech owl and the short-eared owl, the esophagus consists of a simple, thin-walled, greatly expansible tube of generally even calibre, while in the Peale's falcon an anterior enlargement that corresponds 1 to or forshadow\u00C2\u00A9 ; the fully developed crop of gr^pivorous birds, is present. The wall possesses the usual structure characteristic of this region, & stratified squamous epithelium, a tunica propria and a muscularis externa composed of two layers of smooth muscle. The wall is generously supplied with glands and several gland types are present. In the Kingfisher, screech owl and short-eared owl, oval glands composed of essentially the same type of cuboidal cells are situated in the epithelium with only a small portion of the basal part of the gland extending into the tunica propria. The excretory duct in the screech owl is short and nearly indistinguish -able, while in the short-eared owl and kingfisher, the ducts are quite long. In the califonnia murre the glands are s t i l l oval in shape, but have sunkc. \ below the epithelium into the connective tissue of the; lamina propria with only the excretory ducts passing through the epith-elium. The gland cells in this bird have become very narrow, t a l l col-umnar cells, thickening and shortening as they united with the low cuboidal cells of the excretory duct. In the Peale's falcon, sparrow hawk and pigeon hawk, a different type of gland can be recognized. Large lobulated glands rather resembling the esophageal glands of the hen (Calhoun 1933) and composed of t a l l columnar mucous secreting cells like those found in the murre are observed. The excretory duct cells are squamous cells of the epithelium, Schreiner (1900) found that i f the number of glands in the esophagus increased too greatly, they tended to remove themselves fjw\u00C2\u00BB/the\" surface area and sink to the under-lying connective tissue. The cells of the excretory ducts would lose their secretory capacity. The glands in the Peale's falcon, sparrow hawk and pigeon hawk are holocrine secretory and sometimes are en-tirely absent frorijthe esophageal wall. With mucicarmine, a character-istic colour for mucus is obtained for a l l of the esophageal gland cells, including the excretory duct cells of the kingfisher, owls and murre. According to Schaffer's (192ii) classification,all of the glands are of the homocrine monoptychial type. Essentially two methods of secretion, apoctine and holocrine for lubricating the food that passes through the esophagus., are dis-tinguished. In apocrine secretion, present in thejkingfisher, owls and murre, a continual secretion of mucus by the breakdown of the apical parts of the gland cells and in the holocrine type elimina-tion of the entire gland content, including nuclei and cytoplasm occurs. This holocrine secretion is characterized by the Peale's falcon, sparrow-and pigeon hawk. It would be difficult to state which of these two methods of secretion is more effective. In the apocrine type, secre-tion is always present while in the holocrine type, time is necessary for the regeneration of the gland. When the food of these birds is considered, i t will be noted that the diet of each bird is essentially flesh. The kingfisher vive-a chiifly on fish, while the murre will eat crustaceans in addition. - 3 6 -(Taverner, 19U7). The owls are generally predators on small mammals (Taverner^19U7) and the Peale's falcon and pigeon hawk eat birds (Taverner,19U75 May 1935)\u00E2\u0080\u00A2 The sparrow hawk feeds almost entirely on insects (Taverner, 19h7)\u00C2\u00BB Although as stated above,, the chief food of these birds is; meat of one kind or another, considerable variation Aexists, especially in the structure of the esophagus. In the kingfisher, owls and murre, apocrine glands of similar cellular structure occur, yet the Peale's falcon and pigeon hawks, although they show a preference for birds, bol^ will also eat small mammals, as do the owls, but have an entirely different glandular structure. Their glands are deeply sunkf.;i into the tunica propria and the excretory duct cells are transformed so that they resemble or are the cells of the epithelium. May, (1935), found that hawks were able to go a considerable length of time without eating and that many adult hawks did not capture food more than once in two or three days. The feeding habits thus maybe a significant factor in the type of glandular cell present. The stomach of the bird is divided into two regions, an anterior glandular proventriculus and! a posterior muscular gizzard. The stomach shows less variation in structure than the esophagus. The proventriculus is characterized by the presence of peculiar glands that are found generally in the stomachs of a l l birds. These are composed of masses of simple tubules placed adjacently to each other and radiating in a l l planes about a central excretory duct. The tubules are lined by a single layer of \u00E2\u0080\u00A2'zymogen\" or digestive cells -39-that in the birds investigated are found to be a l l of the: same :: type. Slight variations from species to species can be observed! )only in compactness*, arrangement of tubules and in ce l l size The mucosa shows deep regular crypts and a reduced tunica propria in the kingfisher, murre, sparrow hawk and falcon, while in the o owl the crypts are irregularly branched, and the tunica propria is of appreciable size. A muscularis mucosa i s present in the kingfisher: and murre, but i s completely absent in the flesh-eating birds ( the owl, falcon, pigeon hawk and sparrow hawk). Friedman (1939) states that in birds, both acid and pepsin are elaborated by one c e l l . The author also observed only one type of c e l l . The gizzards generally possessed a keratinoid lining, a glandular layer that secretes the lining and a heavy smooth, muscular layer that is more or less uniform in size in the kingfisher, screech owl, Peale&s falcon and sparrow hank. In the murre modification of the gizzard takes place towardr the development of a grinding structure whereby the muscles develop heavily on the dorsal and ventral sides and the central cavity becomes considerably reduced. The keratinoid lining is thicker than that of the other birds, reaching almost the thickness present in the grain-eaters* It may be relevant to mention the Acarried out by Broussay (1935) in which sheftthe diet in a great horned owl from meat to vegetable; and produced an alteration in the gizzard structure. This change was not distinguishable from the outside, from the rest of the stomach. The gizzard became partly separated by a constriction from the rest of the stomach. The mucosa showed newly developed rugae -40-and longitudinal folds similar to those of a gizzard of a young grain-eating bird. As far as thm writer can determine no distinct relation can be drawn between the structure of the tract and the consistency of the food. Birds show considerable adaptability in their food habits. -4r-LITBRATURE CITED Babkin, B. P. 1944, Secretory Mechanisms of the Digestive Glands* Paul B. Hoeber Inc. Medical Book Department of Harper and Brothers, New York. Baker, J . R. a 1945. Cytological Technique. 2nd ed. Methuen and Co. Ltd, London Barthels, Phiiipp. 1895. Beitrag zur Histologie des Oesophagus der tfogel, Zs. f. wi\u00C2\u00BBs. Zool. 59s 655-689 Bauer, Moritz. 1901. Beitrage zur Histologie des Muskelmagens der Vogel. Arch, f. micr. Anat., 571 653-676 Beddard, F. E. 1898. The Structure and Classification of Birds. Longmans, Green and Co. London. Bensely, R, R, and Bensley, S. H. 1938 Handbook of Histological and Cytologidal Technique. University of Chicago Press, Chicago. Bergmann, C. 1862. Einiges uber den Drusenmagen der Vogel. Arch. Anat. Physiol, wiss. Med., pp. 581-587 Berlin, W. 1852-53. Bijdrage tot de spijsvertering der Vogels. Nederl.Lancet, pp. 57-68 cited from Cazin, M. (1888) -42-Bodian, D. 1936. A New Method for Staining Nerve Fibres in Mounte d Paraffin Section. Anat. Rec.j 65: 89-97-Calhoun, M. L. 1933. The Microscopic Anatomy of the Digestive Tract of Gallus Domesticus. Iowa State Coll. J. Sci. 7, 1933 - 261-380. CQZXn, M. . ^ ^ ^ i : ^ d l d\u00C2\u00BB-\u00C2\u00BB\\u00C2\u00ABH\u00C2\u00AB rt.a^.ua. 1886. Recherches sur la Structure de l'estomac des oiseaux. C.R. Acad. Sci., 102:1031-1033. Cazin, M. 1887. Glandes Gastriques a mucus et a ferment chez les oiseaux. C.R. Acad. Sci., 104: 590-592. Cozin, M. 1888. Recherches anatomiques, histologiques, et embryologiques sur l'appareil gastrique des oiseaux. Ann. Des Sc. Nat. Zool., 7th Series, 4:177-323 Curshman, H. 1866 - Zur Histologie-des Muskelmagen der Vogel. Zs. wiss Zool., 16:224-235. Cited from Cozin (1888) Cuvier, G. 1805. Lecons d'anatomie comp. 2nd 8 V Paris, cited from Cozin, M. (1888) Darcus, S. J. 1930 Notes on the Birds of the Northern part of the Queen Charlotte Islands in 1927. Canadian Field Naturalist 44:45-49. Flovsr, I860. On the Structure of the Gizzard of the Nicobar Pigeon and other Granivorous Birds. Proc. Zool. Soc. pp. 330-336. Friedman, M. H. F. 1939* Gastric Secretion in Birds. J. Cell, and Camp. Physiol., V.13, No. 2 219-234. _ . Galigher, A. E. *^ ,J; J \" 1934* The Essentials of Practical Microtechnique \u00E2\u0080\u00A2 Albert E. Galigher, Inc. Laboratory of Microtechnique. Berkeley, California. Garrod, A. H. 1872. On the Mechanisms of the Gizzard of Birds. Proc. Zool. Soc., London. April 16, pp. 525-529. Hasse. 1865. Beitrage zur Histologie des Vogelmagen. Zs. f. rat. Med., 28:1-31, cited from Cozin (1888) Home, E. 1814. Lectures on Comparative Anatomy. Lecture 3 and 4 (On the digestive organs of birds) cited from Bauer, Moritz (1901) Hunter, John 1786. Cited from M. Cozin(1888) Recherches anatomiques, histologiques, et embryologiques sur l'appareil gastrique des oiseaux. Ann. des Sc. Nat. Zool., 7th Series. 4*177-323. Hyman, L. H. 1947* Comparative; Vertebrate Anatomy, 8th Impression. The University of Chicago Press. Chicago, Illinois, Kaden, L, 1936. Uber Epithel und Brusen des Vogelschundes, Zool, Jahrb, Abst. Anat, u Out. 61 (4):421-466. Kingsley, J. S\u00C2\u00BB 1926. Comparative Anatomy of the Vertebrates. P. Blakiston's Son and Co. Philadelphia. Klein, E. 1881 Esophagus und Magen in Strickers* Handbueh der Lehre von den Geweben des Menschen undobr Thiere., 1:497-539, cited from Cozin (1888) Lendrura, A. C. 1944. On the Cutting of Tough and Hard Tissues Embedded in Paraffin. Stain Tech. 19:143-144. Leydig, F. 1857. Lehrbucfi-der Histologied?s Menschen und der Thiere. Cited \u00E2\u0080\u00A2 ^ from Cozin, M. (188Q) Idllie, R, D. 1948 Histopathologic Technique, The Blakiston Co, Philadelphia, May, J. B, 1935. The Hawks of North America. The National Association of - 4 5 -Audubon Societies* H* Milne-Edwards, 1857-1881* Leoons sur la Bhysiologie et l'anatomie oomparee* ;cited from Cazin(l888) Molin, R. 1853* Sugle stomaohi delgi uooelli* Denkschr* Akad* Wiss*, Wien* 2 Abt. 3\u00C2\u00ABl-24. 'eited from Bauer(190l) Pantin, C.F.A. 1946* Notes on Miorosoopial Technique for Zoologists* Cambridge University* Reaumur 1752* Cited from M* Casin, 1888* Recherches anatomiques, histologiques, et embryologiques sur l'appareil gastrique des oiseaux* Ann* des* So* Nat* Zool.* 7th Series, 4t177-323* Sohaffer, J* 1924* Zur Einteilung der Hautdrusen. Anfct* Anz* 57t353\u00C2\u00AB ;Sited from Babkin(l944) Schreiner 1900. Beltrage zur Histologie und Embryologie des Vorderdarmes der Vogel in Ztsohr* Wiss* Zool* 68* xoited from Kaden(1936) -46-Sheer, B. T. 1948. Comparative Physiology. John w i l e y and Sons Inc. New York. Taverner, P. A. 1947\u00E2\u0080\u00A2 ^^irds of Canada. The Musson Book Company, Ltd., Toronto. Wiedersheim, R. E. 1872. Die feinern Strukturverhaltnisse der Drusen in Muskelmagen der Vogel. Arch. f. mikr. Anat., 8:435-452. \u00E2\u0080\u00A2 Wiedershsheim, R. E. and Parker W. N. 1907 Comparative Anatomy of Vertebrates. MacMillan Co., New York. HATE I Fig, 1 Relation of the digestive tract of the kingfisher to the surrounding area, a. Tongue b. Hyoid apparatus c. Esophagus d. Trachea e. Syrinx f. Bronchus g. Falciform ligament h. Liver (cut) i . Proventriculus j . Gizzard k. Duodenum 1, Ventral ligament m. Rectum a PLATE II Fig. 2 Relation of the digestive tract of the owl to the surrounding area. a. Tongue b. Hyoid c. Esophagus d. Trachea e\u00C2\u00BB Syrinx f\u00C2\u00BB Bronchus g. Falciform ligament h\u00C2\u00BB Liver i\u00C2\u00BB Proventriculus j . Gizzard k. Duodenum 1. Ventral ligament m. Rectum P L B T E 11 9 PLATE III Diagrammatic representation of the relative shapes of the esophagus and stomach ofr Fig. 3 Kingfisher a. Esophagus b. Crop evidence c. Proventriculus d. Gizzard e. Duodenum Fig. h California murre Fig. f? Screech owl Fig. 6 Peale's falcon Pig# 7 Sparrow hawk Fig. 8 Pigeon hawk. I PLATE IV Fig. 9 Kingfisher. Anterior esophagus. Mallory's triple 60X a. Epithelium b. Lamina propria c. Muscularis externa d. Tunica adventitia Fig. 10 Kingfisher. Esophagus. Haematoxylin and carmine ll|0X a. Epithelium b. Lamina propria c. Esophageal gland d. Longitudinal layer of muscular externa PLATE IV FIG. 10 PLATE V Figi 11 Kingfisher. Esophageal Oil immersion 1253X a. Basal gland cell b. Duct cell c. Nucleus d. Granular cytoplasm e. Epithelium f. Lamina propria glands. Mallory's triple. F (G. 11 PLATE VI Fig. 12 Kingfisher. Longitudinal muscle. Short foot method for silver impregnation of reticulum with Van Gieson counterstain 63OX a. Longitudinal smooth muscle bundle enclosed in a connective tissue sheath. b. Reticulum surrounding bundles of muscle c. Circular muscle of muscularis externa d. Short reticular fibres around each muscle c e l l e. Nucleus f. Clear area around nucleus g. Lamina propria h. Fibroblast i . Blood vessel Fig. 13 California murre. Longitudinal smooth muscle. Mallory's triple. 63OX a. Longitudinal smooth muscle b. Nucleus c. Loose connective tissue between the muscle bundles. FIG 13 PLATE VII. Fig* lit. California murre. Posterior esophagus. Mallory's triple. 60X a. Epithelium b. Lamina propria c. Muscularis externa d. Tunica adventitia Fig. 15 California murre. Esophagus. Haematoxylin and carmine ll*OX a. Epithelium b. Lamina propria c. Esophageal gland F IG. 15 PLATE VIII. Fig . 16 California murre. Esophageal glands. Mallory's triple 630X a. Basal gland cell b\u00C2\u00BB Duct cel l c. Nucleus d. Granular cytoplasm e. Epithelium Fig. 17* California murre. Lauina propria. Verhoeff's elastic tissue stain LhOX a. Lamina propria b. Elastic fibres c. Fibroblasts d. Lymphocytes e. Artery f. Vein PLATE VIII FIG 17 PLATE IX Fig. 18. Screech owl. Esophagus. Mallory's triple 60X a. Epithelium b. Lamina propria c. Muscularis externa d. Tunica adventitia Fig. 1? Screech owl. Esophagus. Haemztoxylin and Carmine lUOX a. Epithelium b. Lamina propria * c. Esophageal glands PLATE X. Fig. 20. Screech Owl. Esophageal gland. Mallory's triple 630X a. Basal gland cells b. Excretory duct cells c. Epithelium d. Lamina propria Fig. 21 Short-eared owl. Esophageal gland. Mallory's triple 630X a. Basal Gland cell b. Duct cell c. Nucleus d. Granular cytoplasm e. Epithelium f. Lamina propria FIG.2T PLATE XI. Fig, 22. Screech owl. Esophagus. Short foot method for silver impregnation of reticulum . II4OX a. Basement membrane b. Reticulum surrounding the muscle fibres. J PLATE XI a b FIG. 22 PLATE XII Fig, 23\u00C2\u00AB Peale's falcon. Anterior esophagus. Mallory's triple 60X a. Epithelium b. Lamina propria c. Muscularis externa d. Tunica adventitia Fig. 2 l u Peale's falcon. Anterior esophagus. Van Gieson 60X a. Epithelium b. Laaina propria c. Muscularis externa d. Tunica adventitia e. Esophageal gland PLATE XIII Fig. 25. Peale's falcon. Esophagus near the proventriculas* Haematoxylin and carmine LUOX a. Epithelium b. Lamina propria c. Esophageal gland Fig* 26* Peale's falcon. Epithelium. Verheeff's elastic tissue stain and eosin 63OX a* Stratum Malpighi b. Stratum corneum c. Lamina propria d* Fibroblasts e. Vein FfG. 25 FIG. 26 PLA.TE XIV Fig* 27\u00E2\u0080\u00A2 Peale's falcon. Gland before secretion. Verhaeff's elastic tissue stain and eosin 63OX a. Esophageal gland cell* . b. Primary gland cells c. Connective tissue capsule d. Capillary e. Lamina propria f. Fibroblast. Fig* 2 8 . Peale's falcon. Gland at beginning of secretion. Mallory's triple 63OX a. Esophageal gland cell b. Nucleus c. Beginning of the breakdown of the cytoplasm d. Vein e. Capillaries f. Primary gland cell PLATE XIV FIG. 28 PIATE XV. Fig. 29\u00E2\u0080\u00A2 Peale's falcon. Esophageal gland nearing end secretion. Haematoxylin and eosin 630X a. Connective tissue capsule b. Nuclei of gland cells c. Broken down cytoplasm Fig* 30 Peale's falcon. Esophageal gland secreting. Haematoxylin and eosin 63OX a. Glandular lumen lined with epithelium b. Squamous epithelium c. Glandular content being extruded d. Lamina propria papillae PLATE XV FfG.30 PLATE XVI Fig. 31 Peale's falcon. Esophageal glands at various stages .pf secretion. Showing the excretory cavity through the epithelium. Haematoxylin and eosin LUOX a. Esophageal gland. b. Tunica propria c. Blood vessels d. Excretory duct cut at various levels e. Space remaining after secretion. Fig\u00C2\u00BB 3 2 . Peale's falcon. Esophagus after secretion. Verhoeffs elastic tissue stain 63OX a. Epithelium b. Lamina propria c. Blood vessel d. Primary gland cells e. Lymphocytes i PLATE XVII Pig* 33\u00C2\u00AB Sparrowjhawk. Esophagus. Mallory's triple 60X a. Epithelium b\u00C2\u00BB Lamina propria c, Esophageal gland d. Muscularis externa with contraction bands showing in the circular layer* Fig# 3U\u00C2\u00BB Sparrow hawk. Esophageal glands. Haematoxylin and carmine 60X a. Esophageal gland b. Epithelium c. Lamina propria d\u00C2\u00AB Fibroblasts PLATE XVTII Fig* 35* Sparrow hawk. Gland during secretion. Mallory's triple 630X A* Glandular epithelium. b. Connective tissue capsule PLATE XVIII FIG. 35 PLATE XIX Fig\u00C2\u00BB.36. Kingfisher. Proventriculus. Short Foot method for silver impregnation of reticulum and Van Gieson 60X a. Epithelium b\u00C2\u00BB Lamina propria c\u00C2\u00BB Muscularis mucosa d\u00C2\u00BB Deep proventricular gland e. Submucosa \u00C2\u00A3\u00E2\u0080\u00A2 Longitudinal smooth muscles f. Circular smooth muscle d e f FIG. 36 S PIATE XX Fig. 37\u00E2\u0080\u00A2 Kingfisher proventriculus. Mallory's triple lUOX a. Faveolae gastricae b. Lamina propria c. Muscularis mucosa d. Submucosa e. Deep proventricular gland f. Central collecting ducts g. Capillary Fig. 38 Kingfisher. Deep proventricular gland tubules. Mallory's triple. 63OX a. Cross section of tubule b. Reticulum surrounding lobule and containing blood capillaries. c. Zymogen cell d. Nucleus (chromatin pattern very regular) e. Interlobular connective tissue f\u00E2\u0080\u00A2 Intralobular connective tissue PLATE XX FfG- 38 PLATE XXI Fig. 39 Magramatio three dimensional view of the proventricular wall* a. FoveolaE gastricae b. Plica c. Trough d. Excretory duct. e. Cross section of tubules f. Long section of tubules g. Lobular gland h. Intralobular tubule i . Interlobular connective tissue Intralobular connective tissue PLATE XXI FIG. 3 9 -PLATE XXII Fig\u00C2\u00BB 1*0\u00C2\u00BB California murre. Proventriculus. HBedenhain's-Azan 60X a. Epithelium b\u00C2\u00AB Lamina propria c. Muscularis mucosa d\u00C2\u00BB Deep proventricular gland e. Submucosa f. Muscularis externa FIG- 40 PLATE m i l Fig. I 4 I . California murre. Proventricular excretory duct joining gastric crypt. Mallory's triple lijOX a. Gastric crypt b. Excretory duct c. Deep proventricular gland tubules d. Columnar epithelium Fig. 1*2. California murre. Proventricular gland tubules. Heiridenhain1s-azan 630X a. Tubule (cross section) b. Zymogen cel l c. Interlobular connective tissue d. Intralobular connective tissue PLATE XXItl PLATE XXIV Fig* k3\u00C2\u00BB California murre. Proventriculus. Short Foot method for silver impregnation of reticulum. 60X a. Gastric crypt b. Lamina propria c. Muscularis mucosa ^ .d. Submucosa e. Blood vessels and nerves in the base of the gastric ridges. f. Muscularis externa g. Central collecting cavity of deep gland showing basement membrane. PLATE XXIV FfG/43 PLATE XXV Fig. lib* Screech owl. Preventriculus. Mallory's triple 6OX a. Epithelium b. Gastric crypt c. Tunica propria d. Deep proventricular gland e. Muscularis externa Fig\u00C2\u00AB U5\u00C2\u00BB Screech owl. Mucosa of proventriculus. Mallory's triple HiOX a. Epithelium b. Gastric crypt c. Tunica propria d. Excretory duct. e. Side branch of excretory duct. PLATE XXV FfG-45 PLATE XXVI Fig* U6m Screech owl. Longitudinal and transverse section of the deep gland tubules* Heindenhain1s-azan. a* Interlobular connective tissue b* Zymogan cell c* Cross section of tubule d. Longitudinal section of tubule Fig* U7* Screech owl* Nerve ganglion. lodian's silver stain* a* Tunica adventitia b* Circular layer of muscularis externa c* Nerve ganglion of the myenteric plexus PLATE XXVII Fig. U8. Peale's falcon, Proventriculus, Mallory's triple 60X a. Epithelium b* Tunica propria c. Gastric crypt Fig. U9\u00C2\u00BB Peale's falcon* Gland tubules cross section. Verhoeff's elastic tissue stain 630X a* Zymogen cell b* Lumen c. Reticulum around iubule d. Blood ce l l PLATE XXV If FIG. 49 PLATE XXVTIT Fig\u00C2\u00AB 50\u00C2\u00AB Peale's falcon. Gastric mucosa. Mallory's triple UjOX a. Epithelium. b\u00C2\u00BB Tunica propria c. Gland lobe d. Excretory duct e\u00C2\u00AB Secretory tubules PLATE XXIX Fig* 51 \u00E2\u0080\u00A2 Sparrow hawk. Proventriculus. Heindenhain\u00E2\u0080\u00A2s-azan 60X a* Epithelium b\u00C2\u00BB Tunica propria c. Deep proventricular gland d. Muscularis externa e. Tunica adventitia PLATE XXX: Fig, 52, Sparrow Hawk, Proventriculus. Heindenhain's 1U0X a. Epithelium. b. Gastric crypt c. Gland lobe d. Excretory cavity Fig, 53, Sparrow Hawk. Proventricular gland tubules. Heindenhains'-azan, 630X a. Gland tubule b. Zymogen c e l l c. Intralobular connective tissue FIG. 52 h FIG-53 PLATE XXXI Drawings of the sphincters observed between the gizzard and the duodenum of the following birds: (Surface view, looking into the cavity of the duodenum.) Fig* 5U\u00C2\u00BB Kingfisher. Sphincter. 15X a. Duodenal lumen b* Five bulbous muscular projections from the duodenal lumen* Fig* 55* California murre. Sphincter 15X a* Duodenal lumen b* Muscle band surrounding the opening of the duodenum. Fig* 56* Screech Owl. Sphincter a. Duodenal lumen. 15X b. Muscle surrounding the opening. Fig* 57 \u00E2\u0080\u00A2 Peale's falcon. Sphincter* a. Duodenal lumen b* Muscle surrounding the opening of the duodenum* c* Bulbous projections from the duodenal cavity* Fi&. 56 FIG. 57. PLATE XXXII Fig* 5>8\u00C2\u00BB Kingfisher. Gizzard (thickest wall) Short Foot method for the silver impregnation of reticulum and Mallory's triple 60X a* Kerotinoid layer b. Tubular gizzard gland c. Muscularis mucosa d. Submucosa e. Muscularis externa f\u00C2\u00AB Blood vessel FfG. 55 PLATE X f f l l l Fig, 59\u00E2\u0080\u00A2 Kingfisher gizzard. (Thinnest wall) Mallory's triple 60X. a* Keratinoid layer. b. Tubular gizzard gland c. Submucosa d. Muscularis externa e. Tunica adventitia f. Artery g. Vein* PLATE XXXIV Fig* 60* Kingfisher. Gizzard glands. Verhoeff's elastic tissue stain 63OX a* Gizzard gland b* Cuboidal epithelium c. Lumen of gland containing keratinoid secretion d. Lamina propria e. Muscularis mucosa f\u00E2\u0080\u00A2 Blood vessel FIG- 60 HATE XXXV Fig* 61 Kingfisher* Nerve fibre embedded in the smooth muscle of the gizzard. Mallory's triple 63OX a. Nerve fibre b* Smooth muscle c Fat PLATE X X X V c FIG-61 PLATE XXXVI Diagrammatic, longitudinal and transverse sections of the gizzard of the California murre, to show the gross arrangement of the muscle. (Dorsal side toward the top of the plate). Fig. 62. Longitudinal section of the gizzard a. Smooth muscle b. Glandular layer c. Keratin lining Fig. 63 Transverse section of the gizzard. a. Smooth muscle b. Glandular layer c. Keratin lining. PLRTE XXXVI. b. c. F I G . 6 2 . FIG. 6 3 . PLATE XXXVII Fig* 6lu California murre* Gizzard. Haematoxylin and eosin 60X* a* Keratinoid lining* b* Glandular layer c. Lamina propria d* Muscularis externa PLATE XXXVIII Fig* 6S>\u00C2\u00AB California murre. Gizzard glands. Haematoxylin and eosin. 630X. A. Gizzard gland b. Cuboidal epithelium c. Lumen of gland containing keratinoid secretion d. Lanina propria e. Blood vessel f. Muscularis externa PLATE XX XV HI FIG 65 PLATE XXXIX Fig* 66 Screech Owl. Gizzard. Haematoxylin and eosin \u00C2\u00A3OX a. Keratinoid layer b* Glandular layer c. Tunica propria d. Muscularis externa e. Tunica adventitia F IG. 6 6 PLATE XL Fig. 67 Screech owl. Transitional area between proventriculus and gizzard, Haematoxylin and eosin 63OX a. Epithelium b. Tunica propria c. Fibroblasts PLATE XL PLATE XLI Fig* 68* Screech Owl. Gizzard glands. Haematoxylin and eosin 630X a* Epithelium b. Keratinoid layer c. Capillary d\u00C2\u00BB Neck of tubular gizzard gland e. Gizzard gland f\u00E2\u0080\u00A2 Colorless globules in the apical cells FfG. 6 8 PLATE XLII Fig. 69. Peales falcon gizzard. Haematoxylin and eosin 60X a. Keratinoid layer* b* Glandular layer c* Tunica propria d. Dense band of connective tissue enclosing groups of glands* e. Submucosa f. Muscularis externa PLATE XLtl FIG69 1 PLATE XLIII Fig* 70* Peale's falcon gizzard glands, Haematoxylin and eosin 630X a. Keratlnoid lining. b. Gizzard glands c. Apical cells of the gizzard ridges PLATE XLIII FIG. 70 PLATE XLIV Fig* 71 Sparrow Hawk. Gizzard. Mallory's Phosphotungstic Icid Haematoxylin 60X a. Keratinoid layer b. Glandular layer* c. Tunica propria d. Dense band of connective tissue e. Muscularis externa PLATE XL? Fig. 72 Sparrow hawk gizzard glands. Mallory's phosphot-ungstic acid haematoxylin 63OX a. Keratinoid lining b. Gizzard gland cell "@en . "Thesis/Dissertation"@en . "10.14288/1.0106805"@en . "eng"@en . "Zoology"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "The comparative histology of the esophagus and stomach of birds of different food habits"@en . "Text"@en . "http://hdl.handle.net/2429/41242"@en .