Aromatase expression in the accessory olfactory bulb. A, Whole brain distribution of arom+ neurons (red) was visualized by crossing a transgenic mouse line expressing Cre in arom+ neurons with a tdTomato reporter line (grey: autofluorescence for contrast). B, Arom+ fibers and cell bodies were visualized in the AOB and not in the MOB. C, Arom+ neurons were sparsely located in the dorsolateral olfactory tract (AOBdLOT), granule cell layer (AOBGCL), and mitral cell layer (AOBMCL). Arrows indicate the arom+ fiber, with intercalated arom+ cells, in the AOB.