BLASTOCYST PROTEASE AND IMPLANTATION: EFFECT OF OVARIECTOMY AND PROGESTERONE SUBSTITUTION IN THE RABBIT

Abstract

Protease activity in the rabbit trophoblast is demonstrated by a substrate film technique. The dissolution of egg coverings and the penetration of the trophoblast into the uterine epithelium are accompanied by a sharp maximum of proteolytic activity. After ovariectomy at 6 days post coitum, blastocysts are unable to dissolve egg coverings and to implant. These eggs do not have normal values of protease activity and a normal histochemical pattern of its distribution. Following progesterone application in ovariectomized does, enzyme activity and implantation processes are normal. The possible involvement of uterine protease inhibitors in the hormonal regulations is discussed.