Identification of injury-induced mitotic cells in adult rat cerebral cortex by neuron-specific markers.

Adult rat brains were injured by partial decortication. Four days later, the brains were examined for mitotic cells that were immunostained for neuronal markers: the neuron-specific enolase (NSE) and neurofilaments (NF). Of the 30 rats stained for NSE, 15 were found to have NSE-positive cells containing mitotic figures; of the 25 rats stained for NF, 12 possessed NF-positive cells in mitosis. Most of the mitotic neurons were granule cells and small- and medium-size pyramidal cells and were located in cortical layer III within 500 microns from the wound margin. Although a rare phenomenon, mitosis of neurons in the neocortex of mature mammalian brains may reflect neuronal plasticity in response to injury.