Pre- and post-developmental neurogenesis in primates

The [H-3]TdR or bromodeoxyuridine (BrdU) methods for marking DNA replication were used to determine time of origin of over 125 classes of neurons in the 34 structures of the macaque monkey central nervous system. The analysis revealed that each neuronal class is generated in a precisely defined developmental period, the duration of which did not depend on the size and final number of neurons in a given structure. An exception was the granule cell class of the olfactory bulb and dentate gyrus that continues genesis at a low rate even after sexual maturity. Thus, most neurons of the primate brain, including cerebral cortex last the entire life span and are normally not renewable. Overcoming resistance of the adult primate's brain to acquisition of functionally competent neurons as a form of therapy would benefit from insight into why neurogenesis normally ceases at a specific developmental period as well as why there are species-specific and regional differences in the capacity for neurogenesis. (C) 2002 Elsevier Science B.V. All rights reserved.