Sexually mature, male coyotes were injected with [3H]thymidine to estimate (1) the duration of one cycle of the seminiferous epithelium, and (2) epididymal sperm transport time.
The mean duration of spermatogenic stages 1 to 8 was estimated to be 3·4, 2·1, 0·5, 1·4, 1·8, 1·7, 1·5 and 1·3 days, respectively. The total duration of one cycle of the seminiferous epithelium was 13·6 days. Radioactive spermatozoa were observed in the caput epididymidis 40 days after [3H]thymidine injection, but data suggested that they may arrive as early as 37·4 days. Radioactive spermatozoa first appeared in the ejaculate of one male 52 days after [3H]thymidine injection, indicating that the epididymal sperm transport time is about 14 days.