[Electron microscopic study of an experimental contusion cataract of a Japanese monkey].

The traumatic cataract was experimentally induced in the lens of a Japanese monkey and observed with the electron microscope. The purpose of this study was to shed some light on the origin of the cataract caused by various factors. The clinical examinations of the experimental animal showed the opacity of the posterior subcapsular cortex. Electronmicroscopic investigations revealed that lens fibers within the opaque region increased in number of mitochondrion, rough surfaced endoplasmic reticulum and other organelles when compared with those in the clinically normal region of the lens. Furthermore, the intercellular space in the opaque region increased to such an extent that large extracellular vacuoles were formed. Many of these lens fibers became swollen and decreased the interdigitation. Some swollen cells showed sparse arrangement of their cytoplasmic filaments. These morphological changes showed an acceleration of water absorption of the lens fibers from a relatively early stage of the traumatic contusion cataract. The increase in number of mitochondrion in such swollen (hydropic) fibers may play an important role in this process. The present experiment suggests that the appearance of so-called hydropic cells is an initial change in the cataractous lens.