The extracellular matrix of the human optic nerve.

The nerve fibers of the optic nerve are enclosed and segmented by extracellular matrix. With immunostains, we localized collagen types I through VI, laminin, and fibronectin in frozen sections of the extracellular matrix of the prelaminar, laminar, and retrolaminar human optic nerve. The internal limiting lamina of the optic nerve has an extracellular composition similar to the thicker adjacent retinal internal limiting lamina. We confirmed that the lamina cribrosa contains type IV collagen and laminin, whereas the sclera does not. The septa of the retrolaminar optic nerve appear as vascular inward extensions of the pia mater. The glial tube that lines the optic nerve extends forward from the retrolaminar optic nerve through the lamina cribrosa to end anteriorly at the retinal pigment epithelium. It does not separate the optic nerve from the adjacent sensory retina.