ENDOCRINE INFLUENCES ON IMPLANTATION AND DECIDUOMA FORMATION12

Abstract

It has been well established (Rothchild and Meyer, 1942) that deciduoma formation is dependent on adequate amounts of progestational hormone and that estrogenic substances, even in minute amounts, will inhibit the reaction if present just prior to the eliciting stimulus. It is also well known (Allen, 1931; Selye and McKeown, 1935; Peckham and Greene, 1947) that the deciduomal reaction in the rat can be elicited through the 7th day of pregnancy but not thereafter. Two explanations have been offered for the loss of endometrial reactivity after the 7th day: (a) Reduction in progesterone secretion below levels necessary for reactivity, (b) Appearance of inhibitory agents. The first of these possibilities is eliminated by the finding (Peckham and Greene, 1949) that reactivity of the endometrium cannot be restored by the administration of even large amounts of progesterone. In order to investigate the possible role of inhibitory factors, the effect of removal of various structures which might be sources of inhibitors was determined.