Ultrastructural evidence for a close relationship between dopamine cell processes and blood capillary walls in Macaca monkey and rat retina.

In the retina, tyrosine-hydroxylase (TH) antiserum specifically labels intrinsic dopamine (DA)-neurons. In order to clarify the relationship between capillaries and DA-processes already observed by light microscopy, we have performed TH-immunocytochemistry on rat and monkey retinas at the electron microscope level. Close contacts were observed between DA-varicosities and the basal lamina of both pericytes and endothelial cells. As in the brain, these anatomical findings suggest that intrinsic DA-neurons could contribute to the regulation of local retinal blood flow and/or permeability.