Morphological studies on the horizontal and amacrine cells of the teleost retina

Abstract

The unusually large external, medial and internal horizontal cells, the stellate, piriform, interstitial and displaced amacrine cells were studied in the teleost retina, by light microscopy, using the silver techniques of Cajal, Rio Hortega and Bielschowsky. The fibrillar structure, oval nucleus, osmotic, metabolic and electrophysiological behavior, and the lack of axonal and synaptic structures, suggest that the cells described are glial cells rather than neurons. The cellular origin of the different S-potentials is discussed. The above-mentioned cells, which participate in the retinal non-photochemical excitability control and in the processing of the colour difference signals, are denominated “controller cells” and possibly represent an intermediary form of nervous elements between typical neurons and glial cells.