Unidirectional vesicular transport mechanism in retinal vessels.

When horseradish peroxidase (HRP) is introduced into the bloodstream, it is retained in the lumen of the retinal vessels (blood-retina barrier). In this paper, we report that when the same tracer is injected into the vitreous body, it penetrates the lumen of retinal vessels by transcellular vesicular transport. This unidirectional movement of macromolecules out of the eye is not inhibited by ouabain, fluoroacetate, or low temperatures.