Ultrastructural study of hemangiomas. 1. Capillary hemangioma of the skin.

The fine structure of capillary hemangiomas from the skin of six young adults was investigated. All the vessels had non-fenestrated endothelial cells. Their intercellular junctions had tight junctions, but desmosome-like structures were also present. Cytoplasmic filaments (50-100A in width) as well as microtubular bodies were present in some of the endothelial cells. The bodies were approximately 0.1 micron in diameter and up to 0.5 micron in length. Subendothelial basement membrane was present and sometimes multilaminated. Pericytes had a feature of endothelial cells, fibroblasts, or smooth muscle cells. "Fibrous long-spacing collagen fibrils" (periodicity: 700-1500A) were seen in the vicinity of pericyte basement membranes or in the intervascular spaces.