VISUALIZATION OF MITOTIC RADIAL GLIAL LINEAGE CELLS IN THE DEVELOPINGRAT-BRAIN BY CDC2 KINASE-PHOSPHORYLATED VIMENTIN

Although accumulating data reveal patterns of proliferation, migration , and differentiation of neuronal lineage cells in the developing brai n, gliogenesis in the brain has not been well elucidated. In the rat b rain, vimentin is selectively expressed in radial glia and in their pr ogeny, not in oligodendrocytes or neurons from embryonic day 15 (E15) until postnatal day 15 (P15). Here we examined mitotic radial glial Li neage cells in the rat brain E17-P7, using the monoclonal antibody 4A4 , which recognizes vimentin phosphorylated by a mitosis-specific kinas e, cdc2 kinase. In the neocortex, mainly radial glia in the ventricula r zone, but not their progeny, underwent cell division. In contrast, n ot only radial glia but also various types of radial glial progeny inc luding Bergmann glia continued to proliferate in the cerebellum. Radia l glia in the neocortex divided horizontally, obliquely, and verticall y against the ventricular surface. The percentage of the vertical divi sion increased with progress in the stage of development, concurrently with the decrease of the population of horizontal divisions. Thus, th e monoclonal antibody 4A4 provides an useful tool to label mitotic gli a in the developing brain and revealed different patterns of gliogenes is in the neocortex and cerebellum. A possibility is discussed that th e dynamics of mitotic orientation observed here may be related to the change of the pattern of gliogenesis during development. (C) 1998 Wile y-Liss, Inc.