Assembly of 100 nm periodic fibrils (type VI collagen) in human infant corneal stroma.

An experimental model for the age-related changes in the extracellular matrix of the human cornea was developed. Human infant corneal stroma in which no long-spacing collagen occurred naturally was treated with 20 mM adenosine triphosphate (ATP). The ATP-treated cornea was observed and compared with nontreated control specimens by electron microscopy. Numerous 100 nm periodic fibrils which resembled long-spacing collagen were formed by the treatment. These experimentally formed fibrils appeared to attract and aggregate the collagen fibrils with D-periodicity, which indicated a connection between type VI and type I collagen. By ruthenium red staining, the cross-bands of the 100 nm periodic fibrils were positively stained, indicating that glycosaminoglycans or proteoglycans were involved in the formation of these fibrils.