Transmission electron micrograph showing collagen fibrils in longitudinal view from a patient with glaucoma. The a-e banding is visualized by uranyl acetate staining of charged amino acid residues in the constituent collagen molecules. This specimen is also stained with a cationic dye to reveal interfibrillar proteoglycans. Although the fibrils look normal these proteoglycans are reduced in this area supporting the theory that abnormal proteoglycans are a cause of glaucoma.