A direct evidence for the involvement of prostaglandin F2α in the first step of estrone-induced blastocyst implantation in the spayed rat

Abstract The effect of prostaglandin F 2α (PGF 2α ) on blastocyst implantation in spayed rats has been studied. In preliminary experiments, the first implantation sites were observed 8 – 12 hours after a single injection of estrone in ovariectomized and progesterone-conditioned rats. Intraluminal instillation of PGF 2α into the right uterine horn 8 – 10 h after the estrone Injection increased the number of implantation sites. Even treatment with PGF 2α without previous estrone injection induced the first step of blastocyst implantation as shown by uterine dye site reaction (Niagara-blue test). The results are discussed with regard to the possible role of PGF 2α in the regulation of the blastocyst implantation processes in the rat.