Maturation of sperm motility in the epididymis of the common marmoset (Callithrix jacchus) and the cynomolgus monkey (Macaca fascicularis).

The acquisition by spermatozoa of the capacity for movement upon liberation from the epididymal duct into buffer is one of the obvious changes associated with sperm maturation and, hence, studies of sperm kinematics might provide good indices for sperm maturation. Profiles of development in the movement pattern of spermatozoa taken from six regions of the epididymis were established in marmoset and cynomolgus monkeys using computer-assisted sperm analysis. Motion of spermatozoa from initial regions was sluggish and irregular, then developed in the more distal region into erratic movement effected by an increase in the vigour of flagellation as reflected by curvilinear velocity. The tendency of immature spermatozoa to display circular motion was more common in the marmoset than in the cynomolgus monkey. In the marmoset the most drastic changes in percentage motility and kinematic parameters of spermatozoa occurred between the distal caput and the proximal corpus; maximal values for these parameters were found around the distal corpus epididymis. For the cynomolgus spermatozoa the sharpest gain in percentage motility was also achieved between the caput and proximal corpus epididymis, but with full kinematic development in the proximal cauda epididymis. These maturational changes were not synchronous among spermatozoa from the same site as they moved along the epididymis, as reflected in the heterogeneity of each sample in the kinematic properties of individual spermatozoa, especially those from the proximal corpus epididymis. The maturational profiles in the monkeys are comparable to the situation in the human, for which they may provide a useful model.