Ultrastructural Location of Extracellular Matrix Components in the Optic Nerve Head

The distributions of laminin and collagen types I through V were determined in optic nerve heads of cynomolgus monkeys using colloidal gold immunoelectron microscopy. Collagen types I and III localized to striated collagen fibrils in arterial walls throughout the optic nerve head and to fibrils comprising the core of the lamina cribrosa beams and optic nerve septa. Collagen type IV and laminin localized to basement membranes of all blood vessels and to basement membranes of astrocytes that lie between the laminar beams and line the optic nerve septa and pia mater. Collagen type V was detected both in striated collagen fibrils and in vascular and astrocyte basement membranes. These results provide a detailed understanding of the optic nerve head extracellular matrix distribution and illustrate a sensitive method for future study of its role in glaucomatous optic nerve damage.