AN ESTROGEN-DEPENDENT GLYCOPROTEIN IS SYNTHESIZED AND RELEASED FROM THE OVIDUCT IN A TEMPORAL-SPECIFIC AND REGION-SPECIFIC MANNER DURING EARLY-PREGNANCY IN THE EWE

Administration of estradiol-17beta (E) to ovariectomized (ovx) sheep r esults in the synthesis and release of an M(r) 90 000-92 000 glycoprot ein into the oviductal lumen and into culture medium of ampullar expla nts (Biol Reprod 1992; 47:889-902). The objective of this study was to determine when and from what region of the oviduct the M(r) 90 000-92 000 glycoprotein is synthesized and released during early pregnancy. Estrous ewes were bred to intact rams of known fertility, and oviducts were obtained at estrus (Day 0) and at Days 1.5, 2, 3, 4, 6, and 16 o f pregnancy. Pregnancy was verified by the presence of a fertilized eg g or developing conceptus and a functional corpus luteum. Oviductal se cretions were collected by flushing oviducts with saline and by explan t culture. The oviductal fimbria, ampulla, and isthmus were individual ly cultured (24 h) in the presence of H-3-leucine (H-3-leu) or H-3-glu cosamine (H-3-glcN). The presence of the M(r) 90 000-92 000 glycoprote in in oviductal flushing and culture medium was determined by fluorogr aphy and Western blotting. The M(r) 90 000-92 000 protein was present in SDS gels and blots of oviductal flushing from animals through Days 4-6 of pregnancy, but not in flushing from Day 16 pregnant animals or from ovx, untreated animals. This protein was present in H-3-leu- and H-3-glcN-labeled culture medium of the oviductal ampulla (Days 0, 1. 5 , 2, 3, 4, 6, and 16) and fimbria (Days 0, 1. 5, 2, 3, and 4) during e arly pregnancy. The M(r) 90 000-92 000 protein was not detected in ovi ductal ampulla or fimbria culture medium obtained from ovx animals, no r was it present in culture medium of the isthmus oviduct obtained fro m estrous and pregnant animals. These data show that the E-dependent M (r) 90 000-92 000 glycoprotein is synthesized and released by the ovid uct in a temporally and regionally specific manner during early pregna ncy as the gametes and fertilized egg are traversing the tube and prio r to a systemic rise in progesterone.