Immunohistochemical study of human retinal astroglia.

Immunocytochemical localization of glial fibrillary acidic protein (GFAP) has been used to study astrocyte distribution and morphology in whole mounted human retinas and vertical sections. Two types of astrocytes can be distinguished: elongated astrocytes are located in the nerve fibre layer (NFL); and star-shaped astrocytes are found in the ganglion cell layer (GCL). Astroglial processes join to form bundles. The bundles formed by the elongated astrocytes lie along and separate the nerve fibre bundles. Processes from star-shaped astrocytes reach towards other star-shaped astrocytes and towards the vessels to form a morphologically honeycombed plexus. These astrocytes also send other processes towards the internal nuclear layer (INL), forming an irregular plexus which accompanies the GCL capillaries that extend into the INL. Often, the cell bodies of the star-shaped GCL astrocytes lie over vessels and form cell clusters. Finally, none of the retinas examined for this study evidenced the "perivascular astrocytes" described by Wolter in the human retina.