The ultrastructural characteristics of the spermatozoa stored in the cauda epididymidis in Chinese soft-shelled turtle Pelodiscus sinensis during the breeding season

► We describe the ultrastructural characteristics of spermatozoa in Chinese soft-shelled turtle. ► Immature spermatozoa also observed in cauda epididymidis during breeding season. ► Spermatozoa transferred to the oviduct might include those immature ones.