The basal plasma membrane and lamina densa of uterine epithelial cells are both altered during early pregnancy and by ovarian hormones in the rat.

Changes in the basal plasma membrane and lamina densa of uterine epithelial cells have been studied in the rat during early pregnancy and under the influence of progesterone and oestrogen. Both the basal plasma membrane and lamina densa become increasingly tortuous by day 6 of pregnancy and this condition is found to be predominantly influenced by progesterone. Oestrogen, either alone or in combination with progesterone, has a much lesser effect. The lamina densa increases in thickness by day 6 of pregnancy and again progesterone is found to have the major influence. These alterations are discussed in the context of implantation of the blastocyst and we highlight the differing effect that ovarian hormones have on different regions of the plasma membrane of uterine epithelial cells.