Radial glial cells are present in the velum medullare of adult monkeys

As a rule, in thin mammalian CNS tissues such as the median eminence and the retina, radial glia remains the dominating macroglia in adulthood, whereas in most other regions of the brain radial glial is substituted by multipolar macroglia i.e. astroglia. The Velum medullare is another thin CNS tissue but there are no reports on the dominating macroglia forms of this structure. Thus, Golgi-impregnated sections of adult monkey brains were studied for the presence of radial glial cells. Indeed, this structure was found to be transversed by many radial glial fibres terminating with pial endfeet whereas in adjacent thick brain tissues the glia limitans was formed by marginal astrocytes. It is concluded that fibrous radial glia may dominate in adult mammalian and even primate CNS tissues with a thickness of up to 1 mm.