Abstract
The components of the thready material in skin lesions of pseudoxanthoma elasticum, recessive Type I, were analyzed. Immunoelectron microscopic observation revealed the presence of fibrinogen in the thready material. Part of the fine fibrils in the thready material was sensitive to collagenase. The thready material was also stained by ruthenium red. The thready material is composed apparently of fibrinogen, collagenous protein and glycoprotein.