Effects of canine oviduct epithelial cells on movement and capacitation ofhomologous spermatozoa in vitro

In this study, the interaction between canine sperms and oviduct epithelial cells (OECs) was examined in vitro. The oviducts of eight bitches in the f ollicular (F-) phase and six bitches in the luteal (L-) phase were removed under halothane inhalation anesthesia. The entire oviduct was opened longit udinally, and the oviductal epithelium of bitches in the F- and L-phases wa s scraped with a scalpel into tissue culture medium (Eagle's MEM) containin g 10% estrous bitch serum and 10% diestrous bitch serum, respectively. The OEC collected were preincubated for 24 h and then coincubated with ejaculat ed canine sperms at 38 degreesC under an atmosphere of 5% CO2 in air. The p ercentages of sperms exhibiting active tail movement (% TM), hyperactivated sperms (% HA), and acrosome-reacted sperms (% AR) were investigated until 72 h after the start of coincubation. The percentage of sperms labeled with fluoresceinated Ca indicator (% Ca) was evaluated to assess the influx of Ca into sperms cytoplasm during capacitation. Canine sperms attached to bot h ciliated OEC and non-ciliated OEC. All of the mean % TM of the OEC-bindin g sperms in the F-OEC and L-OEC media after 24, 48, and 72 h of coincubatio n were significantly higher than the values of the freely swimming sperms ( P less than or equal to 0.01). Conversely, the mean % AR and % Ca of the OE C-binding sperms were significantly lower (P < 0.01). All of the mean % H-A and % AR of the freely swimming sperms in the F-OEC medium after 24, 48, a nd 72 h of coincubation were significantly higher than the values of the sp erms in the L-OEC medium (P < 0.01). These results indicate that attachment of canine sperms to the OEC prolongs their viability and motility and inhi bits Ca influx into the sperms and sperm capacitation. These phenomena may be responsible for maintaining the active movement and the fertile life of canine sperms in homologous oviducts. (C) 2001 Elsevier Science B.V. All ri ghts reserved.