IMMUNOHISTOCHEMICAL STUDY OF HUMAN RETINAL ASTROGLIA

Immunocytochemical localization of glial fibrillary acidic protein (GF AP) has been used to study astrocyte distribution and morphology in wh ole mounted human retinas and vertical sections. Two types of astrocyt es can be distinguished: elongated astrocytes are located in the nerve fibre layer (NFL); and star-shaped astrocytes are found in the gangli on cell layer (GCL). Astroglial processes join to form bundles. The bu ndles formed by the elongated astrocytes lie along and separate the ne rve fibre bundles. Processes from star-shaped astrocytes reach towards other star-shaped astrocytes and towards the vessels to form a morpho logically honeycombed plexus. These astrocytes also send other process es towards the internal nuclear layer (INL), forming an irregular plex us which accompanies the GCL capillaries that extend into the INL. Oft en, the cell bodies of the star-shaped GCL astrocytes lie over vessels and form cell clusters. Finally, none of the retinas examined for thi s study evidenced the ''perivascular astrocytes'' described by Welter in the human retina.