Structural specializations of human retinal glial cells

Electron microscopy and immunohistochemistry have been used to study the structural specializations of astrocyte and Muller glia cells in human retinas. The astrocytes and Muller cells contribute to the formation of the internal limiting membrane, the retina, the blood vessel glial limiting membranes and the glial sheaths of the ganglion cells. Two types of junctions were observed among retinal glial cells. Adherent junctions were found between astrocytes and Muller cells, and between adjacent astrocytes. Gap junctions were only observed between astrocyte processes, These similarities suggest that astrocytes and Muller cells can perform the same functions in human retinas. Finally, the ''perivascular astrocyte of Wolter'', related only to the blood vessels, was not found. All the retinal astrocytes have the same ultrastructural characteristics, confirming the absence of these astroglial cells in human retinas observed by immunohistochemical techniques. Copyright (C) 1996 Elsevier Science Ltd.