This study was undertaken to determine the modulation of uterine function by chorionic gonadotrophin (CG) in a nonhuman primate. Infusion of recombinant human CG (hCG) between days 6 and 10 post ovulation initiated the endoreplication of the uterine surface epithelium to form distinct epithelial plaques. These plaque cells stained intensely for cytokeratin and the proliferating cell nuclear antigen. The stromal fibroblasts below the epithelial plaques stained positively for ␣-smooth muscle actin (␣SMA). Expression of ␣SMA is associated with the initiation of decidualization in the baboon endometrium. Synthesis of the glandular secretory protein glycodelin, as assessed by Western blot analysis, was markedly up-regulated by hCG, and this increase was confirmed by immunocytochemistry, Northern blot analysis, and reverse transcriptase-PCR. To determine whether hCG directly modulated these uterine responses, we treated ovariectomized baboons sequentially with estradiol and progesterone to mimic the hormonal profile of the normal menstrual cycle. Infusion of hCG into the oviduct of steroidhormone-treated ovariectomized baboons induced the expression of ␣SMA in the stromal cells and glycodelin in the glandular epithelium. The epithelial plaque reaction, however, was not readily evident. These studies demonstrate a physiological effect of CG on the uterine endometrium in vivo and suggest that the primate blastocyst signal, like the blastocyst signals of other species, modulates the uterine environment prior to implantation.

The estradiol-dominated baboon oviduct synthesizes and secretes a glycoprotein (mol wt, 120,000) that binds to oocyte zona pellucida in vivo. This glycoprotein separates into two major isoelectric variants (pl 8.0 and 4.5) on two-dimensional electrophoretic gels. This study was undertaken to further characterize the steroid-controlled gene expression of this glycoprotein. A recombinant cDNA library was prepared to poly(A)+ RNA isolated from oviducts obtained from estradiol-treated baboons. The library was screened with a polyclonal antibody prepared against the acidic component (pl 4.5) of the glycoprotein. A single positive plaque was purified. Digestion of the recombinant plasmid with EcoRI revealed fragments of 230 and 1000 basepairs. The antibody used to screen the library was epitope selected against the fusion protein produced by the purified recombinant phage. The epitope-selected antibody, when incubated with Western blots of oviductal explant culture medium obtained from estradiol-treated baboons, recognized both the acidic and the basic variants of the glycoprotein. Northern blot hybridization with a 32P-labeled insert indicated that a single message of 2.8 kilobases was present in oviducts obtained from estradiol-treated baboons; no hybridization was detectable to RNA from oviducts obtained from progesterone-treated baboons. A mRNA of comparable size was also found in human, hamster, rabbit, and mouse oviduct tissue. In vitro translation of oviductal poly(A)+ RNA from an estradiol-treated baboon followed by immunoprecipitation with the polyclonal antibody against the acidic component indicated that the protein component of the oviductal glycoprotein had a mol wt of 66,000.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of this study was to identify major proteins synthesized by the human oviduct and to determine if the ability of the human oviduct to synthesize these proteins was correlated with a specific stage(s) of the menstrual cycle. Oviducts, obtained from normal menstrual and immediately postpartum women, were minced and cultured in the presence of labeled precursors. The culture medium was analyzed for newly synthesized proteins by electrophoresis, followed by fluorography. One-dimensional gel electrophoretic analysis of culture medium of oviducts obtained at midcycle revealed a major diffuse band in the 120,000-130,000 mol wt (Mr) region which was greatly diminished in intensity or nondetectable in the media of oviducts obtained at all other stages of the cycle. Two-dimensional gel electrophoresis resolved the 120,000-130,000 Mr region into two major proteins, one basic and one acidic. Both proteins were intensely labeled with glucosamine, and the basic protein also incorporated leucine and methionine. Western blots of culture media incubated with antibodies against human placental proteins (PP) demonstrated that PP4 and PP7 were released throughout the cycle, while PP14 was present only at the late luteal stage of the cycle. This study demonstrates that human oviducts continue to synthesize and release macromolecules during organ culture. Additionally, the synthesis of some of these proteins appeared to be stage specific. The Mr 120,000-130,000 glycoproteins are of particular interest since they were observed in medium from midcycle oviducts, a period when the oviduct participates in gamete transport and embryo development.

The baboon oviductal epithelium differentiates into a tall columnar epithelium consisting of ciliated and secretory cells during the follicular phase of the menstrual cycle in response to rising oestradiol levels. The apical tips of these secretory cells are filled with membrane-bound secretory granules. During the luteal phase when progesterone levels are elevated, the epithelium regresses and deciliation occurs. Analysis of secretory proteins obtained from explant culture media by SDS-PAGE followed by fluorography or Western blots has revealed that the baboon oviduct synthesizes and secretes a high molecular weight glycoprotein during the follicular phase of the cycle. Immunocytochemistry demonstrated that this oviductal glycoprotein is localized to the secretory granules of epithelial secretory cells, is oviduct specific, and that following secretion the oviductal glycoprotein binds to the zona pellucida and perivitelline space of ovulated oocytes and embryos within the oviduct. Similar proteins have been characterized in other mammalian species. cDNA data show that the complete coding sequence is 2228 bp for a protein of 623 amino acids. A Genbank search showed that baboon oviductal glycoprotein has high homology to other oviductal glycoprotein sequences at both the nucleotide and amino acid levels. Studies conducted to date probing the biological function of oviductal glycoprotein indicate that this protein plays a role in prefertilization reproductive events (sperm capacitation; sperm-zona binding; zona penetration). Additional experiments are needed to reveal a specific function and mechanism for this molecule.