Organization of collagen types I and V in the embryonic chicken cornea

The distribution and organization of type I and type V collagens were studied in the embryonic chicken cornea using anti-collagen, type specific, monoclonal antibodies and immunoelectron microscopy. These studies were performed on lathyritic 17-day corneas treated at 4 degrees C or 37 degrees C. At the lower temperature, collagen fibril structure is disrupted; at the higher temperature, normal fibril structure is maintained. Corneas from non-lathyritic 17-day chick embryos, reacted at the two different temperatures, were studied for comparison. In Bowman's membrane, the thin (20 nm) fibrils were labelled by antibodies against both type I and type V collagen under all conditions studied. In the corneal stroma, the striated collagen fibrils (25 nm) were labelled with the antibodies against type I collagen in all cases, and by antibodies against type V collagen under conditions where fibril structure was disrupted. These results are consistent with the concept of heteropolymeric fibrils consisting of both type I and type V collagen molecules assembled such that the epitopes on the type V molecule are unavailable to antibody unless the fibrillar structure is disrupted. We suggest that the interaction of type V collagen with type I collagen may be responsible for the small diameter fibrils and the rigid control of fibril structure found in the cornea.