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Ultrastructural and cytochemical study of mink (Mustela vison) spermatozoa

University of British Columbia

This study was undertaken to investigate the ultra-structure, cytochemistry and maturation changes of mink spermatozoa which are important in biological research and in their relevance to artificial insemination. Mature standard dark mink were used in this study. Spermatozoa were released from the testis and epididymis (caput, corpus and cauda) of the male mink, and were also collected from the vagina of female mink immediately after mating. Conventionally prepared thin sections were observed under a transmission electron microscope. Enzymes were cytochemically localized in spermatozoa. The mink spermatozoon head showed six swellings on the dorsoventral aspects: two connected hump-like structures at the anterior border of the equatorial segment of the acrosome, and one at the postacrosomal sheath on each side. These swellings, which show a strong acid phosphatase activity, appeared to be a species-specific structural feature which might be necessary for the recognition of the ovum or for sperm-ovum attachment in fertilization. The occurrence of the postacrosomal swelling in spermatozoa was significantly increased (p < 0.01) during the passage of spermatozoa through the reproductive tract. Although the total length of the head did not change significantly during the passage of spermatozoa down the reproductive tract, the anterior acrosomal length was significantly decreased (p < 0.001), while the postacrosomal length was significantly increased (p < 0.05). The cell membrane on the peripheral part of the acrosome, with the exception of the tip of the acrosome, was significantly separated (p < 0.05) during the passage of spermatozoa through the reproductive tract. The neck appeared to show dorsoventrally continuous but laterally separated capitulum which was followed by two major and five minor columns, forming at first a striated ring and then joining with the dense fibers.of the axial fiber bundle. Some axoneme remnants were found in the interior of the column bundle. The shape of the annulus was triangular in longitudinal sections. The occurrence of the cytoplasmic droplet was significantly decreased (p < 0.001) during the passage of spermatozoa through the test is and epididymis. The motility of spermatozoa was significantly increased (p < 0.05) as spermatozoa passed the successive parts of the reproductive tract. The activities of acid and alkaline phosphatases, ADPase, ATPase and DOPA oxidase were found to be distributed in the head, middle and principal pieces of epididymal spermatozoa. Glucose-6-phosphatase, 5-nucleotidase, non-specific esterase, malate, succinate, lactate and isocitrate dehydrogenases, and NADH diaphorase activities were seen to be confined to the middle piece, while the esterase and malate dehydrogenase activities extended to the head base. The activity of 6-phosphogluconic dehydrogenase was not detected. Although most enzyme activities of spermatozoa were enhanced during the passage of spermatozoa through the reproductive tract, several enzyme activities (acid and alkaline phosphatases, ADPase, ATPase, and malate dehydrogenase) were distinctly reduced in spermatozoa from ejaculated semen recovered from female mink following mating. The presence of enzyme inhibiting factors in the seminal plasma or female reproductive tract was discussed.

Text

2010-02-25

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http://hdl.handle.net/2429/20895

Animal Science

University of British Columbia

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