ULTRASTRUCTURAL FEATURES AND PATHOGENESIS OF DECAPITATED SPERMATOZOA IN A BOAR

A boar with decapitated spermatozoa was examined. The growth rate and libido were normal. The right testis was in the scrotum, but the left one was intra-abdominal. Ejaculated spermatozoa and tissue specimen fr om both testes were observed by light and electron microscopy. Only ta illess heads and headless tails of spermatozoa were observed in the ej aculate. The ratio of heads to tails was about 1:4. Motility of the he adless tails was about 25%. The proximal extremity in the tail was occ upied by the proximal centriole. The basal plate could not be found in the head dr in the tail. Pathogenesis of decapitated spermatozoa in t he present case was analysed by investigating spermiogenesis in the sc rotal testis. Since the pair of centrioles failed to approach the nucl eus, mechanical connection between the proximal centriole and the nucl eus did not seem to be established. In addition, the basal plate was n ot formed on the nuclear membrane. Since the ratio of tailless heads t o headless tails was also 1:4 in the testis, it was concluded that the heads had already detached the tails in the testis.