The maturation of sperm motility in the epididymis and vas deferens of the vervet monkey, Cercopithecus aethiops.

Among the diverse facets of sperm maturation, changes in motility are conspicuous and hence studies of sperm kinematics might provide good indices for sperm maturation. Accordingly, the maturation of sperm motility in the epididymis and vas deferens of the vervet monkey, Cercopithecus aethiops, was assessed using a computer-aided sperm motility analysis system. The results revealed clear trends in the development of both sperm motility per se and in the movement characteristics of motile spermatozoa from different regions of the epididymis, the vas deferens and the ejaculate, reflecting maturational changes associated with the attainment of functional motility and fertility. Motion of spermatozoa from the caput epididymis was sluggish and irregular. As the spermatozoa moved through the corpus epididymis, motility increased sharply, and continued to improve through the cauda epididymis and vas deferens. Despite the high proportion of motile cells, full maturation of motion capabilities was not completed in spermatozoa from the corpus epididymis. Only once spermatozoa had reached the cauda epididymis and vas deferens did they attain their full vigour, and swam rapidly (greater VCL, VSL and VAP) with straightline trajectories (greater LIN, WOB and STR; lower ALH, MAD and CURV). After acquiring their maximal percentage motility and progressive velocity in the cauda epididymis and vas deferens, a slight decline in motility and vigour occurred in ejaculated spermatozoa, and was possibly associated with the ageing of stored spermatozoa. The results from this investigation have revealed clear trends in the maturation of the motility of vervet monkey spermatozoa during their transit through the epididymis and vas deferens and final emergence in the ejaculate, and have provided crucial baseline information on the reproductive physiology of this potentially valuable biomedical model to serve as a reference for future studies in reproductive toxicology.