Ultrastructure of

The fine structural characteristics of hereditary hemorrhagic telangiectasia have been studied in specimens of typical lesions from the tongue of two patients. The large vascular channels were lined with a single layer of endothelial cells on a continuous basement membrane. Smooth muscle cells were present in the walls of the vessels, but appeared to be inadequate as a contractile element. It is suggested that the altered vessels are part of a systemic vascular disorder and are primarily weak, rather than thinned out due to a dilatation of existing vessels.