Cellular and molecular analysis of cryptic testes in dolphins

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In many mammals, the testis is located in the scrotum and is maintained cooler than the deep body temperature. As a result, spermatogenesis is retained to be active. However, the testes in some mammals, such as dolphins, elephants and hyraxes, are present within the abdominal cavity. It remains to be unclear how they can maintain their spermatogenesis under this condition. The present study was designed to examine the relationship between the cryptic testis and the appearance/disappearance of heat shock proteins and lectins. In addition to dolphins, we used experimental cryptorchid mice, gonadally inactive hamster testes and mouse testes at fetal and early postnatal stages (prespermatogenesis). In experimental cryptorchidism of mice, many degenerating cells showed condensation of the nucleus and cytoplasm. TUNEL-positive cells were frequently observed. These data provide evidence that at least some of the cells die by apoptosis. While, hsp 70.2 was expressed in pachytene spermatocytes … More and spermatids. No reaction was detected in cryptorchid testes. In hamster testes, spermatogenesis was severely disrupted at 13 weeks after exposure to a short day cycle. Dolichos biflorus (DBA) agglutinin bound specifically to spermatogonia. DBA bound to only type A spermatogonia in active testes, whereas it bound to type A, intermediate and type B spermatogonia in inactive testes. During prespermatogenesis, characteristic binding patterns of sWGA, VVA and LEA agglutinin were observed in gonocytes. These lectins nay be related to the differentiation of gonocytes. In bottlenose dolphins, hsp86 was strongly positive in type B spermatogonia, spermatocytes and spermatids. Hsp84 was strongly expressed in type B spermatogonia, whereas no reaction was detected in spermatocytes and spermatids. In Risso's dolphins, hsp86 was expressed in pachytene and preleptotene spermatocytes. Hsp84 reacted with type B spermatogonia. These findings suggest that each protein may play a role in the different process of spermatogenesis. Less