Quantitative (stereological) study on the spermatozoal storage capacity of epididymis in rats and monkeys.

AIM

To investigate the spermatozoal production rate of the testis and the spermatozoal storage capacity of the epididymis in monkeys and rats.

METHODS

The 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 adult SD rats on 25 microns-thick methacrylate-embedded sections using a contemporary unbiased and efficient stereological method--the optical disector. The diameter 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 (million, x +/- s) in the monkey, or 179 +/- 31 in the rat; the number of spermatozoa per epididymis was 3235 +/- 1835 in the monkey, or 241 +/- 76 in the rat.

CONCLUSION

A large number of spermatozoa was densely packed and stored in the ductus epididymidis; the epididymal transit time for spermatozoa was around 5 days in monkeys or 11 days in rats.