Mitral and tufted cell-specific transgene expression in Tbx5.0gV transgenic mice. (A1-A4) gapVenus fluorescence in whole-mount brain of Tbx5.0gV transgenic mouse line #1 viewed from dorsal (A1), ventral (A2), lateral (A3) and medial (A4) sides. Strong gapVenus fluorescence is observed in the mitral and tufted cell axons projecting from the olfactory bulb (OB) to various regions of the olfactory cortex. (B, C, D1) Ventral views of whole-mount brains of Tbx5.0gV line #2 (B), #3 (C), and #4 (D1). In all the Tbx5.0gV lines, the accessory OB (AOB) mitral/tufted cells display a higher level of gapVenus expression than the main OB (MOB) mitral and tufted cells, clearly delineating the secondary vomeronasal pathway from the AOB to the amygdaloid nuclei. (D2-D12) Parasagittal (D2, D3) and coronal (D4-D12) brain sections of Tbx5.0gV mouse line #4 immunostained with anti-green fluorescent protein antibody. (D3) A higher magnification of OB. AON, anterior olfactory nucleus; LEnt, lateral entorhinal cortex; lot, lateral olfactory tract; Me, medial amygdaloid nucleus; OTu, olfactory tubercle; Pir, piriform cortex; PMCo, posteromedial cortical amygdaloid nucleus.