THE EFFECTS OF AN INTRA-UTERINE DEVICE ON UTERINE CELL DIVISION AND EPITHELIAL MORPHOLOGY DURING EARLY PREGNANCY IN THE MOUSE

Abstract

SUMMARY Intra-uterine silk threads in mice prevented the development of a normal progestational epithelium and closure of the uterine lumen on day 5 of pregnancy. It seems likely that either of these effects would prevent implantation. The intra-uterine device (IUD) produced an abnormal type of luminal epithelium resembling somewhat the hyperplastic type produced by oestrogen treatment, and characterized by increased cytoplasmic basophilia and irregularly placed, swollen nuclei with prominent nucleoli. The IUD also increased the numbers of mitoses in the luminal epithelium. This mitogenic effect was not due simply to inhibition of the suppressive action of progesterone since mitosis was increased on day 3 when progesterone is probably not involved. All these effects were seen in regions of the uterus remote from the site of the IUD, which suggests that they are caused by factors released into the uterine lumen. In contrast, the effects of the IUD on the glands and stroma appeared to be restricted to the immediate vicinity of the IUD. It is suggested that IUD's might prevent implantation by stimulating the production of substances which antagonize the actions of progesterone on the uterine luminal epithelium.