EFFECT OF BOVINE AMPULLARY AND ISTHMIC OVIDUCTAL FLUID ON MOTILITY, ACROSOME REACTION AND FERTILITY OF BULL SPERMATOZOA

Motility, acrosome reaction and oocyte fertilizing ability were assess ed for bull spermatozoa after incubation in regional (isthmic or ampul lary), bovine oviductal fluid, pooled by stage of the oestrous cycle. Oviductal fluids collected daily from isthmic and ampullary cannulae i mplanted in the same oviduct were divided into pools, representing two oestrous cycle stages, based on daily serum progesterone concentratio ns. Ejaculated bull spermatozoa were incubated for 0-6 h in each type of oviductal fluid. Incubation in isthmic oviductal fluid collected du ring the nonluteal stage, including oestrus and ovulation, decreased o verall sperm motility (from 71.7% motile spermatozoa to 34.0%) and bot h path (78 mu m s(-1) versus 86-89 mu m s-1) and progressive (74 mu m s(-1) versus 83-85 mu m s(-1)) velocities of spermatozoa motion. Sperm atozoa incubated in isthmic, non-luteal oviductal fluid had a higher r ate and extent of sperm acrosome reaction (213% of control versus 136- 161% of control by 2 h incubation) compared with spermatozoa incubated in other oviductal fluid types. However, incubation in nonluteal ampu llary fluid increased the number of spermatozoa, which were both acros ome reacted and live, and able to fertilize bovine ova (88.7% fertiliz ed versus 75-81%). Glycosaminoglycan concentrations were similar among types of oviductal fluid (0.77-0.88 mg ml(-1)). These findings indica te that oviductal fluid differentially affects sperm function, dependi ng on the oviduct region and the stage of the oestrous cycle at which the fluid was obtained.