Search

We have studied the organization of the midbrain radial glia in embryos of Gallotia galloti using the fluorescent lipophilic dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethyl-indocarbocyanine perchlorate (DiI) and the antibodies H5 and RC2. Our goal was to verify if the radial glia takes part in the midbrain boundaries formation and if it defines different zones. Our exam reveals two clear limits, anterior or mesencephalic–diencephalic (m/d) and posterior or mesencephalic–rhombencephalic (m/r), that can be defined as the borders where the midbrain radial glia processes end. Moreover, fasciculate radial glia processes characterize these limits totally or partially. They coincide with gene expression limits and with cytoarchitectonic limits defined by other criteria. Six different subdivisions, five alar and one basal, can be defined according to radial glia distribution, fasciculation, and immunohistochemical features. The ventral part of the alar region is defined by an RC2-positive bundle of radial glial cells. This bundle supposes a trustworthy landmark to point out the tectal/tegmental boundary. We hypothesize that this pattern of midbrain radial glia represents a basic model in amniota. J. Comp. Neurol. 473:162–176, 2004. © 2004 Wiley-Liss, Inc.