High-voltage electron microscopy in eye research. Experimental analysis of the retinal pigment epithelium and choriocapillaris.

The high-voltage electron microscope (HVEM) permits examination of sections much thicker (up to 1 micron) than those usually used in transmission electron microscopy, which are approximately 70 nm in thickness. Two examples of the utility of the HVEM in research on the ultrastructure of the retinal pigment epithelium (RPE) and choriocapillaris are given: the identification of intracytoplasmic tubules that arise from the basal plasma membrane of rat RPE cells; and the tracing of processes arising from choriocapillary endothelial cells during experimentally induced neovascularization. In each case HVEM provided information not easily obtained in routine thin sections.