OESTROGEN AND THE DECIDUAL CELL REACTION OF IMPLANTATION IN MICE

Abstract

SUMMARY: Two non-traumatic methods for the induction of deciduomata were tested in the pseudopregnant mouse. The intra-uterine injection of arachis oil was found to be very effective, but the intraperitoneal injection of pyrathiazine was completely ineffective. Oil and trauma were then compared as decidual stimuli in ovariectomized pseudopregnant mice maintained on exogenous progesterone. When ovariectomy was performed on the afternoon of day 4 of pseudopregnancy both stimuli were effective. When the ovaries were removed on the afternoon of day 3, trauma was still effective but oil no longer induced deciduomata. However, oil retained its effectiveness if 0·025 μg. of oestradiol was injected subcutaneously about 7 hr. before the injection of the oil. It is suggested that the hormonal requirements for decidual cell-induction by oil are similar to those for implantation and that oestrogen is necessary to permit the initial reaction between the oil (or the blastocyst) and the surface of the epithelial cells. Traumatic induction does not require oestrogen because it does not simulate this reaction.