Fractin and TubulinΔCsp6 highlight degenerating axon tracts during turnover of olfactory sensory neurons in the adult mouse brain. Axons terminating in the glomerular layer of the adult olfactory bulb were assessed; the region with axon terminals is indicated by the box in (a). Adjacent sections were stained with CC3 (b), fractin (c) and TubulinΔCsp6 (cTub) (d) (green) along with neurofilament-medium (NFM; red) and the glomeruli were imaged. Fractin and TubulinΔCsp6 highlight structures consistent with fragmented neurites in a subset of glomeruli (indicated by filled arrowheads and hatched circles), likely representing neurites from olfactory sensory neurons undergoing physiological turnover. The olfactory nerve layer composed only of sensory axons, contains the highest density of TubulinΔCsp6 immunoreactive neurites (open arrowhead). Other regions of the olfactory bulb were devoid of neoepitope marker labeling. Scale bar = 50 μm.