Electron microscopic serial sections in a tangential plane through the inner wall of Schlemm's canal and the trabecular meshwork in normal and glaucomatous eyes revealed a characteristic network of elastic-like fibers (cribriform plexus), which is directly connected to the inner wall endothelium by a special fiber system (connecting fibrils). This cribriform plexus is also connected to the ciliary muscle system. Ciliary muscle tendons were found that not only show the same fine structure as the cribriform plexus but also join it. The ciliary muscle tone can therefore directly influence the fiber system of the cribriform plexus and its connections to the inner wall of Schlemm's canal. in eyes with chronic simple glaucoma, three types of plaques in the cribriform meshwork have been described after studies of sagittal sections. A comparison with tangential sections of the same piece of tissue shows that plaques of type II and III are in fact sections through the cribriform plexus and that only type I plaques are a separate entity.