Histological Confirmation of Bulb-x. Photomicrographs of Nissl-stained horizontal section (rostral toward bottom) through cortical frontal pole and olfactory bulbs of unilaterally bulbectomized mouse (Mouse H in Fig. 2). A. Lower magnification view: Note scar tissues and lack of organized neuropil where right olfactory bulb was removed (left side). B. Higher magnification view from intact left bulb ipsilateral to naris occlusion showing bulbar lamina (see region of interest in A, right). Note abnormally thin lamina relative to typical adult mouse olfactory bulb histology. C. Higher magnification view from right side ipsilateral to bulbectomy (see region of interest in A, left). Note apparent lack of organized neuropil, particularly any detectable glomerular structure. This disorganization was confirmed in serial sections throughout the extent of the olfactory bulb in naris occluded subjects and in a sample of normal mice. aob = accessory olfactory bulb; epl = external plexiform layer; gcl = granule cell layer; gl = glomerular layer; ipl = internal plexiform layer; lfp = left frontal pole; lob = left olfactory bulb; mcl = mitral cell layer; onl = olfactory nerve layer; rfp = right frontal pole; Scale bar in A = 250 μm.