Quantitative (stereological) study on the spermatozoal storage capacity ofepididymis in rats and monkeys

To investigate the spermatozoal production rate of the testis and the sperm atozoal storage capacity of the epididymis in monkeys and rats. Methods: Th e number of the late spermatids (steps 13 - 14 in the monkey or steps 15 - 19 in the rat) per testis and the number of spermatozoa per epididymis were estimated in 6 normal adult monkeys (Macaca fascicularis) and 6 normal adu lt SD rats on 25 mum-thick methacrylate-embedded sections using a contempor ary unbiased and efficient stereological method-the optical disector. The d iameter and length of the efferent ductules and ductus epididymidis and the volume of the epididymal fluid in the tubules were also estimated. Results : The total number of the late spermatids per testis was 2902 +/- 749 (mill ion, (x) over bar +/- s) in the monkey, or 179 +/- 31 in the rat; the numbe r of spermatozoa per epididymis was 3235 +/- 1835 in the monkey, or 241 +/- 76 in the rat. Conclusion: A large number of spermatozoa was densely packe d and stored in the ductus epididymidis; the epididymal transit time for sp ermatozoa was around 5 days in monkeys or 11 days in rats.