Collagen type distribution and macromolecular organization of connective tissue in different layers of human skin.

Human skin is composed of several layers which are characterized by a specific macromolecular organization of connective tissue. Three approaches were used to quantify the collagen types present in each of the different layers: biochemical analysis of authentic tissue, metabolic labeling of organ cultures, and metabolic labeling of fibroblast monolayers. We obtained reproducible evidence for a somewhat higher ratio of type III/type I collagen synthesis in the papillary dermis and the subcutaneous fat compared to the reticular layer. Constant amounts of alpha 1 (I) trimers and type V collagen were found in all layers. The degree of hydroxylation of lysine in either type I or type III collagen was the same in any layer of the skin.