ASTROGLIAL INDUCTION OF IN-VIVO ANGIOGENESIS

A purified population of astrocytes was prepared from embryonic rat hy pothalamus. These cells were transplanted into the cerebral cortex of adult rats with survival time of 5 days and studied by glial fibrillar y acidic protein (GFAP) immunohistochemistry and electron microscopy. A progressive gradation from the edges of the implant to the intact ho st tissue was observed in relation to the vascularization process. The regenerating tissue showed cells with cavities resembling capillary c entral lumens and their cytoplasms revealed gold particles when they w ere immunostained for electron microscopy. Dark processes were seen in capillary-like lumens and, on other occasions, evaginations of endoth elial cells were in contact with astroglial processes. These findings lead us to suggest that capillary-like structures might develop from c avitated astroglial cells, which would permit the migration of endothe lial cells into their lumens. Astroglial-endo thelial interactions per sist until endothelial cells are morphologically differentiated. inter pretation of the present that astrocytes might participate directly an d actively in the regulation of capillary formation.