Two- and three-dimensional ultrastructure of endothelium and pericyte interdigitations in capillary of human...

Two- and three-dimensional electron microscopic observation in the immature capillary of the human granulation tissue revealed cytoplasmic interdigitations (CID) between the endothelium and the pericyte. These were composed of a cytoplasmic projection and indentation, and there was a gap space without basement membrane-like components between the two cell membranes. Plasmalemmal vesicles were frequently found locating beneath and/or attached to the cell membranes at the indentated side of the interdigitation. Two kinds of cytoplasmic interdigitation, each having a characteristic configuration, were demonstrated. The CID which was composed of a cytoplasmic projection from the endothelium to the pericyte had a dull-shaped cytoplasmic projection, while the CID which was composed of a cytoplasmic projection from the pericyte to the endothelium had a slender and long finger-like configuration.