Abstract
The corneal endothelium of four presumably normal human eyes, removed at operation, was studied with the electron microscope. Thorotrast had been injected into the anterior chamber a few minutes prior to the enucleation. The Thorotrast particles reached the anterior end of the intercellular space within 3 minutes and had entered Descemet's membrane within 6.5 minutes after injection into the anterior chamber. The pathway of the particles is discussed. The fine structure of the human corneal endothelium is described in detail, and the findings are schematized in a diagram (text, Fig. 30).