Glia of the human retina

The human retina contains three types of glial cells: microglia and two types of macroglia, astrocytes and Muller cells. Macroglia provide homeostatic and metabolic support to photoreceptors and neurons required for neuronal activity. The fovea, the site of the sharpest vision which is astrocyte- and microglia-free, contains two populations of Muller glia: cells which form the Muller cell cone in the foveola and z-shaped Muller cells of the foveal walls. Both populations are characterized by morphological and functional differences. Muller cells of the foveola do not support the activity of photoreceptors and neurons, but provide the structural stability of the foveal tissue and improve the light transmission through the tissue to the photoreceptors. This article gives overviews of the glia of the human retina and the structure and function of both Muller cell types in the fovea, and describes the contributions of astrocytes and Muller cells to the ontogenetic development of the fovea.