ASTROGLIA-MICROVESSEL RELATIONSHIP IN THE DEVELOPING HUMAN TELENCEPHALON

The telencephalon of 12 and 18 week-old human foetuses was examined fo r evidence of astroglia-microvessel relationship. Immature astroglia c ells (radial glia and astroblasts) and astrocytes were immunostained u sing antibodies to the cytoskeletal proteins vimentin (VIM) and glial fibrillary acidic protein (GFAP). The microvessels were detected using an antibody to the blood-brain barrier (BBB)-specific glucose transpo rter GLUT1. Two extracellular matrix (ECM) glycoproteins, laminin (LM) , an endothelial-derived molecule, and tenascin-C (TN-C), a glia-deriv ed molecule, were also analyzed. In the two stages examined, VIM- and GFAP-positive fibers of the radial glia establish close relationships with the radial and periventricular microvessels, which are GLUT1-posi tive and lined by an LM-positive basal lamina-like matrix. At the 18(t h) week, also radial glia transitional forms and immature astrocytes e xhibit extensive contacts with the microvasculature. A TN-C-rich ECM i s revealed around the vascular plexus of ventricular zones at the 12(t h) week, and around the newly growing radial microvessels and the micr ovessel branching sites at the 18(th) week. The observations taken as a whole, suggest that during the telencephalon morphogenesis the immat ure astroglia cells play a role in the early establishment of the dist ribution pattern of the neural microvessels and in their growth and ma turation.