Oviductal sperm storage as a reproductive tactic of turtles.

The oviducts of two species of freshwater turtles were examined throughout the year to determine the distribution of sperm within the oviduct, the locations of stored sperm, and the onset of mating. Sperm were stored in undifferentiated tubules and ducts of submucosal glands at the periphery of large glandular segments of the albumen and uterine regions of the oviduct. Sperm transfer to females commenced in October in Sternotherus odoratus and in January in Trachemys scripta. The role of sperm storage in the annual reproductive cycle of freshwater turtles is evaluated in light of the onset of sperm transfer to females and the timing of ovulation and oviposition. Stored sperm are most likely to be utilized in the fertilization of eggs ovulated in the second and subsequent egg clutches.