IMMUNOGOLD LOCALIZATION OF PORCINE OVIDUCTAL SECRETORY PROTEINS WITHIN THE ZONA-PELLUCIDA, PERIVITELLINE SPACE, AND PLASMA-MEMBRANE OF OVIDUCTAL AND UTERINE OOCYTES AND EARLY EMBRYOS

The objectives of the present study were to develop an antibody probe to the porcine estrogen-dependent oviductal glycoproteins and to deter mine, by use of immunogold electron microscopy, whether these glycopro teins become associated with oviductal and uterine oocytes and early e mbryos. Polyclonal antibody, prepared using the M(r) 75 000-85 000 gly coprotein, separated from other proteins by two-dimensional SDS-PAGE, specifically recognized all three estrogen-dependent glycoproteins (ac idic 75 000-85 000 M(r); acidic 100 000 M(r); basic 100 000 M(r)). In ampullary tissue collected from ovariectomized and estrogen-treated gi lts and from gilts at Day 1 of estrus, gold particles were clustered o ver putative secretory granules restricted to the apical region of sec retory epithelial cells. While follicular oocytes did not react with i mmunoreactive colloidal gold, oviductal and uterine unfertilized oocyt es were found to be density and uniformly labeled by colloidal gold th roughout the zona pellucida, associated with flocculent material in th e perivitelline space, and associated with microvilli and vitelline me mbrane. Similarly, in oviductal (1-4-cell) and unhatched uterine (4-ce ll/blastocyst) embryos, colloidal gold particles were distributed thro ughout the zona pellucida, heavily associated with flocculent material in the perivitelline space, and associated with the plasma membrane o f the blastomeres. Immunoreactive colloidal gold remained detectable w ithin Day 7 hatched uterine embryos, but not with embryos from later d ays. These results further support the proposal that porcine estrogen- dependent oviductal glycoproteins are released into the oviductal lume n, become associated with oviductal and uterine oocytes and early embr yos, and are retained by oocytes and early embryos in the uterus.