Testis structure and sperm packet formation in the phylogenetically basal teleost Pantodon buchholzi

Publication date: March 2019Source: Zoologischer Anzeiger, Volume 279Author(s): Anna Dymek, Anna PecioAbstractPantodon buchholzi is the only extant member of a primitive group within the fish order Osteoglossiformes producing complex sperm and sperm bundles, but neither mode of sperm bundle formation nor testis structure was previously described, therefore our studies provide more details on the reproductive biology of this species' testes based on light and electron microscopy (TEM, SEM).Males of P. buchholzi possess paired testes divided into anterior spermatogenic and posterior aspermatogenic regions modified into testicular glands. The spermatogenic part contains anastomosing seminiferous tubules filled with spermatocysts arranged peripherally around a central lumen filled with secretion. Within the cysts germ cells develop synchronously. At the end of spermiogenesis all spermatids have their heads oriented parallel and in the same direction, surrounded by spherical residual bodies, which are phagocytized by Sertoli cells. This arrangement of spermatozoa is maintained during spermiation and within sperm bundles released into the luminal secretion. Sperm bundles are then transported to the testicular gland, where are stored within the glandular secretion. In addition to tutoring sperm bundles, the testicular gland is also involved in the steroidogenic process.Given that modifications of testis structure, coupled with sperm bundle formation, were features previously descri...

Source: A Journal of Comparative Zoology - February 11, 2019 Category: Zoology Source Type: research