Abstract

Important features of adult neuronal number, location, and type are a consequence of early embryonic events that occur before neurons have differentiated. We have measured cell number during embryogenesis of the rat CNS. Markers that are expressed in the proliferating neuronal precursor are required to study the mechanisms controlling their proliferation and differentiation. By applying immunohistochemistry, fluorescence-activated cell sorting, and 3H-thymidine auto-radiography to dissociated rat CNS cells, we show that the monoclonal antibody Rat 401 recognizes a cell population with proliferative, temporal, and quantitative features expected of neuronal precursors.