Changes during puberty in chromatin condensation, morphology and fertilizing ability of epididymal spermatozoa of the golden hamster

Summary. Male golden hamster sperm acquire complete fertilizing ability at about 48 days of age. In this study hamsters, 27–130 days of age were killed and their male reproductive tracts examined. Sperm were found in the caudae epididymides from 37 days onward. None of the sperm from animals younger than 41 days were capable of fertilizing ova when placed in the uteri of superovulated females. Using flow cytometry of acridine-orange-stained cells, the chromatin condensation in cauda epididymal sperm was investigated. It was seen that DNA from sperm from the younger animals (under 40 days of age) was less tightly bound to protamine than that obtained from mature animals. In summary, the earliest sperm produced by pubertal hamsters were immature with regard to chromatin condensation, morphology, motility, and ability to fertilize ova, and they developed mature characteristics in the period between 40–48 days of age.