Fig. 4
From: The role of the odorant receptors in the formation of the sensory map
Homologous glomeruli within the olfactory bulb (OB). Olfactory sensory neurons (OSNs) expressing the same odorant receptor (OR, depicted as drop shapes with the same color) form one glomerulus on the medial side and one glomerulus on the lateral side of each OB. This couple of glomeruli is indicated as homologous or isofunctional glomeruli because they both processed information related to the same OR. The homologous glomeruli are connected through a link related to external tufted cell (ETC) projections (indicated with green lines connecting the homologous glomeruli, green filled circles), which terminate in the internal plexiform layer (IPL), just underneath the homologous glomerulus on the opposite side of the bulb (depicted by the green lines ending just beneath the homologous glomeruli). This connection is reciprocal. For simplicity, only a few layers of the OB are indicated. GL = glomerular layer, MCL = mitral cell layer, IPL = internal plexiform layer