Ultrastructure of cells in the surface epithelium of the rat uterus during early pregnancy, and the effect of an intrauterine device

Abstract

A marked difference in staining reaction to alkaline toluidine blue was found for the surface epithelial cells of the rat uterus on Day 3 of pregnancy (Day 0 being the day of finding spermatozoa in the vagina). An examination of the morphology of these cells showing differerences in basophilia was undertaken in an attempt to establish whether they represent cells of different ages. Ultrastructural features of cells showing pronounced basophilia included many narrow cisternae of rough endoplasmic reticulum flattened Golgi saccules numerous smooth surfaced apical vesicles of irregular shape and secondary and tertiary lysosomes. By contrast the cells having the weaker basophilia showed many cisternae of rough endoplasmic reticulum which were dilated prominent Golgi apparatus numerous smooth surfaced apical vesicles which were more uniform in shape secondary lysosomes and few teriary lysosomes. It is suggested that the strongly basophilic cells represent the more mature cells of the epithelium. The content of smooth surfaced vesicles in the apical region of luminal epithelial cells were greatly reduced in the presence of an IUD. The IUD may exert its contraceptive effect through an alteration in the formation of a luminal surface coat of the epithelial cells. In control animals this surface coat may permit recognition of the blastocyst prior to implantation. The possibility of modifying the surface coat of the epithelial cells or blastocyst by intrauterine chemical agents could provide a more effective method of regulating fertility.(Full text)