Al. Way et al., INFLUENCE OF BOVINE AMPULLARY AND ISTHMIC OVIDUCTAL FLUID ON SPERM-EGG BINDING AND FERTILIZATION IN-VITRO, Journal of Reproduction and Fertility, 109(1), 1997, pp. 95-101
The objective of this study was to determine the effects of oviductal
fluid on sperm binding and fertilization in vitro when either bovine o
ocytes or both spermatozoa and oocytes are incubated in fluid from dif
ferent regions of the oviduct and at different stages of the oestrous
cycle. Oocytes, or oocytes and spermatozoa, were incubated in nonlutea
l and luteal oviductal fluid obtained from the whole, isthmic or ampul
lary oviduct of dairy cows. Gametes were washed and coincubated in fer
tilization medium for 18 h, and then observed for sperm binding and pe
netration. More spermatozoa bound to oocytes that were preincubated in
nonluteal oviductal fluid than to those that were incubated in luteal
oviductal fluid; however, there were no differences in fertilization
rates between the two treatments. More spermatozoa bound to oocytes in
cubated in isthmic than in ampullary oviductal fluid. However, if both
gametes were incubated in oviductal fluid before their coincubation,
binding was higher when both gametes were incubated in ampullary ovidu
ctal fluid. By reducing the time of coincubation of spermatozoa with t
he oocytes, differences in fertilization rates were seen among the var
ious oviductal fluid treatments. At 14 and 16 h of coincubation, more
oocytes were fertilized if spermatozoa were preincubated in isthmic ov
iductal fluid and oocytes were preincubated in ampullary oviductal flu
id than if both gametes were incubated in whole or ampullary oviductal
fluid. Because both sperm binding to the zona pellucida and fertiliza
tion rates were greater in treatments in which gametes were exposed to
regional oviductal fluid than when they were incubated in whole ovidu
ctal fluid, it is concluded that oviductal fluid from different region
s of the bovine oviduct may play different roles in facilitating ferti
lization.