The Effect of Pilocarpine on the Endothelium Forming the Inner Wall of Schlemm's Canal: An Electron-Microscopic Study in the Monkey Cercopithecus Aethiops

¹ Eye Department, Sabbatsbergs Hospital, the Department of Anatomy, Karolinska Institute, Stockholm
² Department of Physiology, Makerere University College Medical School Kampala, Uganda the Department of Pharmacology, University of Uppsala Sweden

Eight Cercopithecus aethiops monkeys were treated topically in one eye with a dose of pilocarpine that gives a large facility increase. The chamber angles were fixed in buffered osmic acid and the endothelial layer forming the inner wall of Schlemm's canal studied with the electron microscope. Vacuole-like structures, which would include sections through transendothelial channels, were counted, as were sections through the nuclei. The frequency of vacuole-like structures, but not of sections through the nuclei, was reduced by nearly half on the treated side. There was no correlation between this lowering and any pilocarpine effect on facility. It is pointed out that the frequency with which a structure is found in ultrathin sections can be decreased because of a true reduction in incidence or because of a reduction in the chance of being included in a section through changes in shape or size. Thus, the functional significance of the present findings is not clear.