FUNCTIONAL AND MORPHOLOGICAL FEATURES OF SPERMATOZOA MICROASPIRATED FROM THE EPIDIDYMAL REGIONS OF CYNOMOLGUS MONKEYS (MACACA-FASCICULARIS)

In most species examined to date, spermatozoa mature during transit th rough the epididymis to become functionally competent to swim progress ively, fertilize oocytes, and produce viable offspring. In the studies presented here, the status of spermatozoa obtained from the regions o f the epididymis of the cynomolgus monkey (Macaca fascicularis) was ex amined. Epididymal fluid was collected by microaspiration from the cap ut, corpus, and cauda regions. The spermatozoa obtained were evaluated for morphology, motion parameters, and tight zona pellucida binding a nd were compared to spermatozoa collected by electroejaculation. Epidi dymal and ejaculated sperm differed morphologically only in the locati on of the cytoplasmic droplet. Motile sperm recovered by swim-up proce dure exhibited a significantly higher proportion of sperm with more di stal cytoplasmic droplets than the original aspirated samples (p < 0.0 2). Poor duration of movement was most noticeable for corpus spermatoz oa, and to a lesser degree for cauda spermatozoa, when the motion para meters of velocity, linearity, and amplitude of the lateral head were examined. Zona pellucida binding was decreased only for sperm microasp irated from the caput region; sperm obtained from the corpus and cauda regions bound comparably to those collected via electroejaculation. T hese results suggest that by the time cynomolgus sperm reach the corpu s region of the epididymis, they arc functionally competent for tight zona binding. However, these nonhuman primate sperm may not complete t he metabolic changes requisite for sustained sperm motility until reac hing the most distal regions of the epididymis.