High resolution cytochemical study of uterine epithelial cell surface of the rat at identified sites previous to blastocyst-endometrial contract.

A transmission electron microscopy study was carried out in prospective implantation sites in uterine horns of rats of the Long Evans strain. The purpose was to search for possible modifications in glycoproteins of outer coats of endometrial epithelium shortly before blastocyst-endometrial contact Shea's technique (Lanthanum-Alcian blue) was used to visualize glycoproteins. Prospective implantation sites disclosed a rather thin finely granular electrondense layer along the plasma membrane of the surface endometrial cells. In addition, there was a decrease in the number of microvilli as well as a lack of Lanthanum precipitate in junctional complexes. Sites remote from prospective implantation areas, disclosed a thicker electrondense layer of glycoproteins in cell plasma membranes including those of well developed microvilli. The junctional complexes were well depicted by the electrodense lanthanum salt precipitates. These observations suggest that a mechanism other than a more physical contact take place and induce the above changes.