Macroglia cells of the macaque monkey retina.

There are two types of macroglia cells in the macaque monkey retina: Müller cells and astrocytes. Both cell types are in close contact with neuronal structures as well as with the retinal vasculature and are thus well suited for their many physiological tasks. Müller cells ubiquitously traverse the whole thickness of the retina whereas astrocytes are only found in the ganglion cell and nerve fiber layers of vascularized retinal regions. In the adult, astrocytes are very scarce in the central 4 mm around the fovea, a region coinciding with peak Müller cell densities. During development this area is transiently occupied by astrocytes which then disappear during the first postnatal weeks at least in part through apoptosis. Possible reasons for this transiency will be discussed.