Most olfactory neurons were GABAergic, in agreement with previous work (Nagayama et al., 2014), and one was also dopaminergic. We found no mature glutamatergic neurons in the olfactory bulb. However, two neuroblast types (OBNBL1 and OBNBL2), putatively located in the mitral cell layer, may represent immature versions of the olfactory projection neurons, the mitral, and tufted cells. One of them, OBNBL1, expressed the identifying marker of mitral cells, the T-box transcription factor Tbx21.
