FATE OF HAMSTER OVIDUCTIN IN THE OVIDUCT AND UTERUS DURING EARLY GESTATION

Oviductins are a family of glycoproteins which are synthesized and sec reted by oviductal secretory cells and which, upon their secretion in the lumen of the oviduct, become associated with postovulatory oocytes and developing embryos. Recently, we showed that hamster oviductin is maximally secreted in the oviduct at the time of ovulation and is lat er associated with a certain population of uterine epithelial cells, w here it is subsequently endocytosed and degraded. In light of these re sults, this study was conducted to follow the fate of hamster oviducti n in the oviduct and uterus during early gestation. Using a monoclonal antibody against hamster oviductin, immunofluorescence and immunogold labeling revealed that during early gestation, immunoreactivity to ov iductin in the uterus gradually diminished to an almost total disappea rance at time of implantation. However, the strong labeling intensity remained unchanged in the oviduct. Biochemical analyses demonstrated t hat a degradation of oviductin occurs in the uterus, and a loss of imm unoreactivity was also observed as gestation progressed, so that by th e time of implantation, immunoreactivity to oviductin was barely detec table. The decrease of oviductin along the uterine epithelium at the t ime of blastocyst attachment and its final disappearance at implantati on suggest that this glycoprotein could be a potential modulator of ut erine receptivity. (C) 1997 Wiley-Liss, inc.