Three days after unilateral exposure to MeBr, sensory neurons labeled by OR18 riboprobe are completely eliminated from the epithelium on the side exposed to MeBr (CI-129). A, Photomicrograph showing OR18+ OSNs in the nasal cavity on the side where the naris was closed before MeBr exposure. Boxed area is shown at higher magnification in C. D, Side where the naris was open during the MeBr exposure. B, Schematic of the OE showing the location of the photomicrographs. Scale bars: (in A) A, B, 200 μm; C, 50 μm.