The Effect of Fluid From the Cauda Epididymidis, Serum Components and Caffeine Upon the Survival of Diluted Epididymal Hamster Spermatozoa

Summary. When epididymal hamster spermatozoa were diluted in increasing amounts of Tyrode's solution, their survival diminished markedly. If, instead, they were diluted in 20% `cauda epididymidis' fluid (CEF), their survival increased. The active factor of CEF was found to be of low molecular weight and heat stable. If the spermatozoa were diluted in the presence of caffeine or a capacitating medium derived from human serum, their survival was not significantly increased but the rate of those moving was markedly stimulated. Human serum components, but not caffeine—albumin or epididymal fluid—albumin, capacitated hamster spermatozoa. The survival-promoting factor of epididymal fluid did not appear to act through sperm cyclic AMP metabolism.