Evaluation of motility, freezing ability and embryonic development of murine epididymal sperm after coculture with epididymal epithelium.

Murine sperm from the caput, corpus and cauda epididymis were cocultured with epididymal epithelial cells of their own region or more distal regions, in the presence and absence of androgens (testosterone and dihydrotestosterone). Epithelial cell cultures were used 3 or 10 days after preparation in a complex tissue culture medium (Chang's) as plated tubules. The coculture studies involving spermatozoa and oocytes with epithelial cells were carried out in T6 medium. Motility of caput spermatozoa was maintained for 24 h in the presence of day 3 corpus and cauda epithelial cells and hormones but not under other conditions. Likewise, the motility of corpus spermatozoa was maintained for 24 h in the presence of day 3 cauda epithelial cells and hormones but not other conditions. Fertilization of zona-intact oocytes by epididymal spermatozoa was not affected by their coculture for 24 h with epithelial cells but fertilization rates for zone-free oocytes were increased for caput spermatozoa cocultured with more distal epithelial cells. Fertilization rates for both zona-intact and zone-free oocytes were increased for corpus spermatozoa cocultured with more distal cauda epithelial cells. The developmental capacity of embryos derived from caput spermatozoa was not significantly increased by coculture with epithelial cells but those derived from corpus spermatozoa cocultured with cauda epithelial cells were significantly increased. We conclude that the presence of more distal epithelial cells of the mouse epididymis maintains motility in culture, increases the ability of caput and corpus spermatozoa to fertilize zona-free oocytes and increases the developmental capacity of embryos formed from corpus spermatozoa. These observations demonstrate the function of epididymal regions in the maturation of murine spermatozoa for fertilization and embryo development.