Andrology: Evaluation of motility, fertilizing ability and embryonic development of murine epididymal sperm after coculture with epididymal epithelium

Murine sperm from the caput, corpus and cauda epididymis werecocultured with epididymal epithelial cells of their own regionor more distal regions, in the presence and absence of androgens(testosterone and dihydrotestosterone). Epitheial cell cultureswere used 3 or 10 days after preparation in a complex tissueculture medium (Chang's) as plated tubules. The coculture studiesinvolving spermatozoa and oocytes with epithelial cells werecarried out in T6 medium. Motility of caput spermatozoa wasmaintained for 24 h in the presence of day 3 corpus and caudaepithelial cells and hormones but not under other conditions.Likewise, the motility of corpus spermatozoa was maintainedfor 24 h in the presence of day 3 cauda epithelial cells andhormones but not other conditions. Fertilization of zonaintactoocytes by epididymal spermatozoa was not affected by theircoculture for 24 h with epithelial cells but fertilization ratesfor zona-free oocytes were increased for caput spermatozoa coculturedwith more distal epithelial cells. Fertilization rates for bothzona-intact and zona-free oocytes were increased for corpusspermatozoa cocultured with more distal cauda epithelial cells.The developmental capacity of embryos derived from caput spermatozoawas not significantly increased by coculture with epithelialcells but those derived from corpus spermatozoa cocultured withcauda epithelial cells were signilicantly increased. We concludethat the presence of more distal epithelial cells of the mouseepididymis maintains motility in culture, increases the abilityof caput and corpus spermatozoa to fertilize zona-free oocytesand increases the developmental capacity of embryos formed fromcorpus spermatozoa. These observations demonstrate the functionof epididymal regions in the maturation of murine spermatozoafor fertilization and embryo development.