Abstract
Testicular development to 9 months of age has been studied. Seminiferous tubule diameter increased in a linear manner between 13 and 65 days of age, and there was a steep increase in testicular weight with age. At about 9 months the animals weighed 400-500 g and total testicular weight was about 10 g. This relatively large testicular size was correlated with high sperm density in the semen.
Spermatogenesis commenced at about 21-25 days of age, when the first spermatids were found. Spermatozoa appeared in a small proportion of seminiferous tubules by 31-35 days of age, and were seen in the epididymides of an animal of 31 and another of 34 days. Epididymal spermatozoa were consistently present in large numbers after 60 days and this correlated with the increased frequency of mature seminiferous tubules.
Leydig cell size increased rapidly from 13 to about 60 days, then remained constant. Inferences have been drawn from this and the study of spermatogenesis about the level of testosterone secretion.
The results indicate that the male cuis is almost fully grown and sexually mature by about 90 days of age.