ErbB4-positive cells are enriched in the glomerulus and mitral cell layers of olfactory bulb. A, Diagram of mouse brain sagittal section (top) and coronal sections (middle, bottom). Dashed lines b and c of the sagittal section diagram indicate the position of coronal sections. B, Coronal section of ErbB4-reporter mouse brain, 4.28 mm relative to bregma. Area shown is indicated by the rectangle in the middle panel of A. C, Coronal section of ErbB4-reporter; GAD67::GFP mouse brain, 2.68 mm relative to bregma. Area shown is indicated by the rectangle in the bottom panel of A. D, Enlarged image from the boxed area in C. Arrows indicate neurons positive for ErbB4 and GAD67. Empty arrows indicate neurons positive for GAD67 alone. 1, Layer 1; 2/3, layers 2 and 3; 5, layer 5; AON, anterior olfactory nucleus; DLO, dorsal lateral orbital cortex; FrA, frontal association cortex; gl, glomerulus layer; gr, granular layer; ipl, inner plexiform layer; LO, lateral orbital cortex; MO, medial orbital cortex; MOB, main olfactory bulb; ml, mitral layer; opl, outer plexiform layer; PrL, prelimbic cortex; VO, ventral orbital cortex.