Unilateral trauma to the somatosensory cortex increases cell proliferation in the cerebral hemisphere ipsilateral to the CCI/sham. (a) Short-term BrdU incorporation analysis reveals widespread activation of cell proliferation in the cerebral hemisphere ipsilateral to the CCI or sham craniotomy. Mice were processed for anti-BrdU IHC at 74 hours post-procedure following BrdU injections at 0, 24, 48 and 72 hours post-procedure. In each image panel the cerebral hemisphere ipsilateral (IPSI) to the CCI/sham is on the left, the contralateral (CONT) hemisphere is on the right. Scale bar = 1 mm. (b and c) Co-immunolabeling of anti-Iba1 antisera (green), a marker for microglia and macrophages, with anti-BrdU + (red) reveals numerous co-immunoreactive cells in the (b) cortex and (c) striatum of the cerebral hemisphere ipsilateral to the CCI or sham craniotomy. Scale bars = 20 μm. (d and e) Co-immunolabeling with anti-GFAP antisera (green), a marker for reactive astrocytes, reveals astrogliosis in the (d) cortex and (e) striatum of the cerebral hemisphere ipsilateral to the CCI or sham craniotomy but minimal astrocyte contributions to the BrdU + cell population (red). Scale bars = 20 μm. (f) Quantification of immunolabeled cell numbers in the ipsilateral cortex and striatum reveals a graded increase in BrdU + cell numbers with increasing injury severity. Co-immunoreactivity to anti-Iba1 antisera confirms the majority (>50%) of these BrdU + cells are proliferating microglia or macrophages in CCI and sham mice, whereas astrocytes account for only 2-7% of the BrdU + cell population (n = 4-12/group).