Rs. King et al., EFFECT OF BOVINE OVIDUCTAL ESTRUS-ASSOCIATED PROTEIN ON THE ABILITY OF SPERM TO CAPACITATE AND FERTILIZE OOCYTES, Journal of andrology, 15(5), 1994, pp. 468-478
At estrus, an oviduct-specific, estrus-associated glycoprotein (EAP) o
f molecular weight 85-95,000, is secreted by the oviductal epithelium
and found in cannula-derived bovine oviductal fluid (ODF). The objecti
ves of these studies were to determine if bovine sperm were capacitate
d by EAP in vitro, whether this effect differed for EAP derived from O
DF versus conditioned medium from oviduct ampullar explants, and to de
termine if sperm capacitated in vitro with EAP-fertilized bovine eggs.
Sperm were incubated for up to 6 hours with partially purified EAP de
rived from ODF and assessed for capacitation by their ability to under
go the acrosome reaction following exposure to lysophosphatidylcholine
. At 4 hours of incubation, the number of capacitated sperm in treatme
nts containing 50% ODF or EAP plus bovine serum albumin (BSA) was simi
lar, and it was significantly greater than the number of capacitated s
perm in treatments containing antibodies to EAP. Using purified EAP de
rived from ampullar explant-conditioned medium, twice the number of sp
erm were capacitated after 4 hours with EAP from conditioned medium or
with ODF than with treatments containing anti-EAP. The fertilizing ab
ility of sperm incubated with EAP was significantly greater than that
for sperm incubated without EAP or with anti-EAP. We conclude that bov
ine EAP, derived from both ODF and in vitro cultures, promotes sperm f
ertilizing ability.