Capillary-contacting horizontal cells in the rodent retina.

Horizontal cells, the interneurons in the distal retina, provide feedback control of the photoreceptor synaptic output at the first synapse in the visual pathway. This article, using immunohistological and confocal microscopy techniques, presents anatomical evidence that in rat and mouse retina, the horizontal cell processes are in contact with retinal capillaries as are retinal glial cells. This glia-like property of horizontal cells in these two species, also previously reported in tree shrews by Knabe and Ochs (1999), appear to be a more common theme for these neurons than previously appreciated.