Fig. 7. Immunolocalization of m4.1N protein. Immunoperoxidase and indirect immunofluorescence staining was performed on floating 40 μm sections of adult rat brain using the m4.1N antibody; immunohistochemistry was also conducted on select peripheral tissues. A, Mitral cells of the olfactory bulb exhibit intense staining of the cell bodies and dendritic processes (black arrowhead); the nuclei are distinctly negative. Among the m4.1N-positive dendritic processes, discrete varicosities exhibit robust staining. B, The olfactory bulb is devoid of staining when incubated with antibody preabsorbed with the m4.1N fusion protein. C, An indirect immunofluorescence confocal image of the same region of the olfactory bulb demonstrates the dendritic labeling of mitral cells with areas of speckling.Inset, Profiles of dendrites in cross section indicate that m4.1N is found at the outer rim of the processes, consistent with a juxta-membrane localization. D, The granule cell layer (GCL) of the cerebellum exhibits a punctate pattern of immunostaining; there is also robust labeling of the molecular layer (ML). E, No signal is detected in the cerebellum when the preabsorbed antibody is used. F, An indirect immunofluorescence confocal image of the cerebellar granule cell layer demonstrates discrete spots of immunofluorescence in the synaptic glomeruli; a white arrow points to one of the punctate structures. G, In the hippocampus, there is a prominent reticular pattern seen in the granule cell layer of the dentate gyrus (DG) and among the pyramidal cells of CA1–CA3; there is also homogeneous speckling of the molecular layer of the dentate and CA3.H, No immunostaining is detected in the hippocampus with the preabsorbed antibody. I, An indirect immunofluorescence confocal image of the granule cell layer of the dentate gyrus reveals discrete spots of immunofluorescence outlining the cell bodies; a white arrow points to one of the punctate structures. The molecular layer (white arrowheads) exhibits a densely speckled pattern of immunofluorescence. J, Within the retina, there is prominent labeling of the apical dendrite and the cell body of bipolar cells. K, Between the smooth muscle layers of the gastrointestinal tract, there is specific immunostaining of the enteric neurons (black arrowheads). Inset, The punctate pattern of labeling is evident at high magnification. L, In the kidney, there is intense immunostaining of the convoluted tubule epithelia; the collecting tubule epithelia stain in a “checkerboard” pattern, such that alternating cells are positive. The cells of the glomeruli are completely negative (asterisks). Inset, The robust immunostaining of a tubular epithelial cell is shown at higher magnification. Scale bars, A, B,K, 40 μm; C, F, 10 μm;D, E, G, H, 160 μm; I, 12.5 μm; J, 16 μm;L, 80 μm.