An assessment of the fertilizing ability of spermatozoa in the epididymis of the marmoset monkey (Callithrix jacchus)

Abstract

The fertilizing ability of spermatozoa from different regions of the epididymis of the marmoset monkey, C. jacchus, was assessed by determining their rate of fusion with zonaless hamster ova in vitro. This technique tests for functional competence and was validated using epididymal spermatozoa of the hamster whose fertility was measured previously by in vivo fertilization experiments. Some marmoset spermatozoa first acquire the ability to fertilize in the distal caput and proximal corpus epididymidis although the majority become fertile on reaching the proximal cauda region. Acquisition of fertilizing capacity was associated with a change in the degree and character of sperm motility. Modifications to the sperm plasmalemma which allow capacitation and the acrosome reaction to occur are of primary importance for sperm fertility. The development of sperm fertilizing ability in the marmoset is discussed in relation to that in other primates.