Immunogold localization of type IV collagen and laminin in the aging human outflow system

Tissue from the outflow system of six surgically enucleated aged eyes was used for an ultrastructural immunocytochemical study of the distribution of laminin and type IV collagen. The immunogold technique provided precise localization of laminin beneath lining endothelial cells of the inner wall of Schlemm's canal. Laminin labelling was absent in the trabecular beams. Type IV collagen was found in the basement membranes of the trabecular beams and in fine filamentous basement membrane material in the cribriform layer. Electron dense plaques in the cribriform layer labelled positively for laminin in the outer coarse fibrillar zone but not in the electron dense core. Long-spacing collagen was negative for type IV collagen.