Immunoelectron microscopy of type III collagen in normal and scleroderma skin.

Normal and scleroderma skin was studied by indirect immuno-electron microscopy with specific antibodies against Type III collagen. Fine collagen fibrils, 200-400 A in diameter were labeled with antitype III collagen antibodies. These antibodies attached to the collagen fibril forming rings with a 650 A periodicity. Fibrils with more than 600 A in diameter were only labeled with antitype I collagen antibodies. Type III collagen was found around small blood vessels, adipocytes and smooth muscle cells, thus, corresponding to the distribution of reticulin.