Studies on the development of cell contacts and of the intercellular matrix during decidualization in the rat.

Cell contacts between developing decidual cells were examined in thin sections and in replicas of freeze-cleaved tissue of rat uterus. At the time of implantation only puncta adhaerentia were found between stromal cells. Gap junctions appeared 24 h after decidualization and thereafter increased in number and extent. Thus, there is little morphological evidence for a propagation of the initial stimulus for decidualization via gap junctions. An increase in amorphous, extracellular material is noted after decidualization with a concomitant decrease of collagen fibers. This amorphous material probably represents fibrinoid.