Reaction of fresh and frozen bull spermatozoa incubated with fresh and frozen bovine oviduct epithelial cells.

The hypothesis was tested that frozen bovine oviduct epithelial cells (BOEC) could provide a physiologic and standardized system for studying motility and acrosomal changes of fresh and frozen-thawed sperm. The BOEC were collected by lavage from cows and monolayers prepared from both fresh and frozen-thawed cells. Fresh and frozen semen processed from five bulls was extended in a modified Tyrode's medium and coincubated with both types of monolayers at 39 degrees C in 5% CO2 and 95% humidified air. After 5, 10 and 24 h of incubation, percentages of motile, progressively motile and acrosome-reacted unattached sperm were measured. The percentage of motile fresh sperm exceeded the motility of frozen sperm, and more fresh sperm attached to BOEC. More frozen sperm than fresh sperm were acrosome reacted. Fresh and frozen epithelial cells produced similar effects, except sperm motility was higher after 5 h of incubation with fresh BOEC. Thus, the convenient frozen-thawed coincubation protocol provides a practical in vitro system for studying capacitation and the acrosome reaction.