FORMATION OF DECIDUOMATA IN THE LACTATING MOUSE

Abstract

SUMMARY: When the uteri of lactating mice were traumatized from 4 to 16 days post partum, deciduomata were formed in only one of thirty-one animals. However, when progesterone in doses of 0·25 mg or more was administered for 3 days after traumatization, sixteen out of eighteen lactating mice formed deciduomata. It was established that at least 0·35 mg progesterone daily for 7 days is required to induce the decidual reaction in ovariectomized mice. Although there is ample evidence for the secretion of progesterone during lactation in the mouse, the amounts are apparently insufficient to initiate and maintain deciduomata. It is concluded that quantitative differences exist between the pseudopregnancy of lactation and of sterile coitus.