Embryo implantation in the rat uterus induced by epidermal growth factor

The present study was undertaken to determine whether the mechanism of embryo transfer is a factor in the action of epidermal growth factor (EGF) in initiation of implantation. Unilateral intrauterine infusion of 3 microliters buffered saline, or saline containing 1.5 micrograms EGF, plus i.v. injection of 100 micrograms EGF 2 h later resulted in implantation sites in all animals within 48 h. In several animals implantation was also initiated in the non-injected uterine horn. Administration of indomethacin 1 h before the intrauterine injection completely blocked the effect of EGF but not that of 25 ng oestradiol. The results confirm that EGF can replace oestrogen for initiation of implantation provided that the uterine trauma associated with embryo transfer, that is puncture, is provided. The mechanisms involved remain to be resolved.