Rapid spermatogenesis and structural analysis of the manchette in Chinese soft-shelled turtle, Pelodiscus sinensis

Rapid spermatogenesis is a special mode of sperm development pattern discovered in Chinese soft-shelled turtles ( Pelodiscus sinensis ). During the breeding season, numerous immature round spermatids are found in the seminiferous tubules of P. sinensis , but the development process of these cells has not yet been studied. To investigate the fate of these round spermatids, we collected sexually mature P. sinensis in September and analyzed the morphological changes of round spermatids. The results showed that the round spermatids further complete their maturation process in the epididymis. The proportion of round spermatids in the head of the epididymis was significantly higher than that in the tail ( P < 0.001), while the proportion of morphologically mature spermatozoa in the tail of the epididymis was significantly higher than that in the head ( P < 0.0001). In addition, histological approaches including immunohistochemistry, scanning electron microscopy, and fluorescence staining were used to observe the changes in the developmental process, and provided further evidence that round spermatids can complete further maturation in the epididymis. This study provides valuable insights into the mechanisms of spermatogenesis in P. sinensis and contributes to advancing research on reptilian reproductive physiology. • Rapid spermatogenesis pattern discovered in Pelodiscus sinensis . • The round spermatids complete their maturation process in the epididymis. • The spermatogenic cells can detach from the spermatogenic epithelium. • Rapid spermatogenesis increasing the efficiency of sperm production.