Expression of both Ki-67 and DCX sharply decreased with advancing age or life history stages in the sub ventricular zone, rostral migratory stream and sub granular zone of the BALB/c mouse brain. DCX was expressed in similar regions as Ki-67 except for the cerebellum and tectum. In addition, fewer Ki-67 positive cells were also observed in the neocortex, cerebellum and tectum. Ki-67 expression was mainly observed in the olfactory bulb, rostral migratory stream, sub ventricular zone of lateral ventricle and the sub granular zone of the dentate gyrus. To achieve this, Ki-67 and DCX immunohistochemistry was used to assess changes in cell proliferation and neuronal incorporation respectively. The aim of this study was therefore to determine time course changes in neurogenesis in the male BALB/c mouse brain at postnatal ages 1 week to 12 weeks, spanning juvenile, sub adult and adult life history stages. However, previous age-related studies focused mainly on changes in neurogenesis during different stages of adulthood and did not describe changes in neurogenesis through the different life history stages of the animal. Several studies have identified age as one of the strongest regulators of neurogenesis in the mammalian brain.
