Immunohistochemical localization of epidermal growth factor receptor during implantation in the rabbit

Epidermal growth factor receptor was localized immunohistochemically during implantation (gestational days 7 through 14) in the rabbit. During early implantation (days 7 through 9), immunostaining was observed in the cytoplasm and on the surface of the syncytiotrophoblastic knobs. By day 8, immunoreactivity was most pronounced in knobs interacting directly with uterine epithelium but was noted in nonknob cytotrophoblast as well. Fetal membranes, identified by day 10, were stained intensely on all days examined. In later gestation the trophoblast was stained intensely on the surface and in the cytoplasm, with some staining over nuclei. No appreciable changes in the staining pattern were observed after day 10. Uterine epithelium demonstrated epidermal growth factor receptor staining first on the antimesometrial (day 7) and then the paraplacental epidermal (day 9). After day 10, most staining was at the embryo-maternal interphase. These data suggest that the embryo and uterine epithelia can receive signals from their environment during and after implantation through the epidermal growth factor receptor.