The ability of sperm to adhere to and detach from the epithelium appears to be related to their capacitation status. Capacitated hamster and bull sperm bind to oviductal epithelial cells with much lower frequency than uncapacitated sperm. This may be due to changes in the head plasma membrane that occur during capacitation or due to hyperactivated motility associated with the capacitated state that causes the sperm to detach within a short time after making contact. Since some of the capacitation process occurs in the oviduct at a time coincident with sperm-epithelial interaction, it is likely that some aspects of capacitation are modulated though this interaction. flovent inhaler
During sperm-epithelial interaction in vivo, sperm adhere to the apical plasma membrane of oviductal epithelial cells. The presence of a heavily sialylated glycocalyx on the apical plasma membrane of oviductal epithelial cells renders this membrane unique among cellular membranes and allows it to be isolated by differential centrifugation. With this technique, apical plasma membrane fractions have been obtained from the oviductal epithelium of rabbits, horses, and humans. When these apical plasma membrane fractions were suspended in aqueous media, they formed closed, roughly spherical vesicles ranging in diameter from 30 to 300 nm. Staining with ruthenium red revealed that the majority (—85%) of these vesicles formed right side out. When rabbit, equine, or human sperm were incubated with homologous oviductal apical membrane vesicles (oAMV) derived either from preovulatory does and mares or from premenopausal women, oAMV were observed by electron microscopy to bind exclusively to the plasma membrane of the rostral (periacrosomal) region of the sperm head.