The Uterine Epithelium as a Transducer for the Triggering of Decidualization in the Rat

Abstract

In rats and mice, the uterine surface epithelium on Day 5 of pregnancy appears still intact while the decidual reaction is already spreading (Finn, 1977). Therefore the physiological signal from the blastocyst that initiates decidualization must be conveyed in some way through the epithelial layer. Uterine trauma, such as scratching or crushing, can elicit a decidual cell reaction (DCR) in pseudopregnant or adequately sensitized spayed animals, but whereas a “normal” DCR requires previous intervention of small amounts of estrogen (Finn, 1977), traumatic deciduomas can also be obtained with progesterone alone (De Feo, 1967). It has therefore been argued that luteal estrogen primarily acts upon epithelial cells by enabling them to transmit the embryonic message, whereas trauma would bypass this step and act on the stroma directly (Finn and Martin, 1974). Another opinion holds that the epithelium is a compulsory intermediate in any type of DCR, for traumatic procedures would be efficient only if they also damage epithelial cells (Psychoyos, 1974; Thibault, 1978).