A strategy to improve the efficiency of spermatogenesis during the breeding seasons of Pelodiscus sinensis

Abstract The Chinese soft‐shelled turtle ( Pelodiscus sinensis ) is a reptile that undergoes seasonal reproduction. To produce enough spermatozoa during the mating season, immature spermatozoa can be quickly released from the testis. Cell morphological changes related to the maturation process are then completed in the epididymis. In this way, spermatozoa develop simultaneously in the epithelium and lumen of the seminiferous tubules, making sperm production much more efficient, which is a strategy to boost the efficiency of spermatogenesis. Morphological changes of spermatozoa can also occur in vitro. We found that when P. sinensis spermatozoa were maintained in vitro, the head could be transformed into an expanded shape with nucleolus‐like structures appearing inside. The results suggest that the process of morphological changes of P. sinensis sperm is a response to the seasonal reproduction and environmental changes. For most species, spermatogenesis and morphological maturation occur at the epithelium of the seminiferous tubule, but our results offer a new perspective in spermatogenesis of P. sinensis , and explain why spermatozoa can be produced so quickly during the breeding seasons.