Estimate of epididymal transit time in the chimpanzee

During their passage through the epididymis, sperm undergo functional changes which result in their maturation and in their ability to fertilize ova. Maturational changes effected during epididymal transport are attributable to sequential changes in various regions of the plasmalemma of the sperm head and flagella. These functional changes in the plasmalemma result, at least in part, from the sequential binding of proteins secreted by the epididymal epithelium into the epididymal lumen. An estimate of epididymal transit time is essential to such investigations. Time elapsed from a testicular arterial infusion of a single pulse of tritiated-thymidine to the release of 3H-labeled sperm into the lumen of the seminiferous tubule was about 39 days. Seminal fluid-free 3H-labeled sperm first appear in the ejaculate about 41 +/- 1 days post-infusion. Total transit time for 3H-labeled Sd2 sperm released into the tubular lumen to appear in the ejaculate is estimated as the difference between these values. Since total transit time is equal to the seminiferous tubule transit time plus the epididymal transit time, epididymal transit time constitutes some lesser portion of the total transit time of 2 +/- 1 days.