[Cytochemical localization of actin filaments in endothelial cells of rabbit trabecular meshwork].

Localization of actin filaments in the endothelial cells of rabbit trabecular meshwork was studied by the nitrobenzoxadiazole-phallacidin (NBD-ph) staining method for fluorescence microscopy and modified heavy meromyosin (HMM) decoration method for electron microscopy. Endothelial cells stained with NBD-ph exhibited intense fluorescence which was apparently associated with the basal plasma membrane area. By the modified HMM decoration method, labeled actin filaments were readily detected in the prefixed endothelial cells, because of the distinctive arrowhead-like appearance, observed beneath the basal plasma membrane facing the trabecular collagen sheet. The actin filaments were arranged with dual directionality within the bundle. In contrast, intermediate (10nm) filaments in the deeper region of endothelial cells were always unlabeled with HMM. The function of the actin filament bundles in endothelial cells may be to maintain the cell shape and provide contractility of the trabecular meshwork resulting in an alteration of the outflow resistance of aqueous humor drainage.