Glial fibrillary acidic protein expression in the developing human retina.

We have studied the expression of glial fibrillary acidic protein(GFAP), an astrocyte specific protein in the normal developing human retina using anti-GFAP antibody. GFAP positive cells were first detected at 24 gestational weeks(GW) in the nerve fiber and ganglion cell layers in the vicinity of the optic disc. Over subsequent weeks, GFAP positive cells covered larger regions of the retina. Some of the processes of these cells terminated in sucker like end-feet upon blood vessels of the nerve fiber layer. A second population of GFAP positive cells existed as perivascular glia in the nerve fiber layer in the early stage of fetal development. In the adult retina perivascular glia were found on vessels throughout the nerve fiber and in the inner portion of the inner plexiform layers. Staining of Müller cells end-feet was obtained only in the adult retina. These results support the views that in the human retina, GFAP positive cells first appear at 24 GW in the region near the optic disc, covering the whole retina at subsequent ages.