[Three-dimensional structures of the nonpigmented epithelium of the dog ciliary body--application of sodium hydroxide digestion to scanning electron microscopic observation of the ciliary epithelium].

The nonpigmented epithelium (NPE) of the dog ciliary body was three-dimensionally observed by scanning electron microscopy (SEM) using sodium hydroxide digestion. The inner limiting membrane of the NPE and the zonular fibers covering the NPE were completely dissolved in 6N sodium hydroxide for 10-15 minutes at 60 degrees C, although the surface structures of the plasma membrane were remarkably preserved despite the rather rigorous treatment. Thus, the entire surface of the NPE was exposed for SEM. The surface of the NPE at the anterior part of the pars plicata was flat, but many complex processes were observed in the surfaces of the NPE as lateral walls of the middle and posterior parts of the pars plicata, to which the zonular fibers had adhered. The processes were more prominent in the middle portion and gradually flattened near the posterior portion. Many pit-like structures and drumstick-like processes of the plasma membrane were localized at the apex of the ciliary process.