Fig. 3

Projections of olfactory sensory neurons (OSN) to the olfactory bulb (OB). OSNs expressing a given odorant receptor (OR, indicated by drop shapes with the same color) are confined in one of the partially overlapping zones in which the olfactory epithelium has been subdivided along the dorso-ventral (D-V) axis. Within each zone, OSNs expressing different ORs (indicated by drop shapes of different colors) are intermingled. OSNs expressing the same type of ORs project to form glomeruli (filled circle of the same color of the corresponding OSNs) in specific loci of the olfactory bulb (OB). There is a correspondence between the zonal organization of the epithelium along the Dorso-Ventral (D-V) axis and the projection of OSNs along the D-V axis of the OB. OSNs harbored in the most dorsal zone of the epithelium project to the most dorsal area of the bulb, whereas OSNs located in the most ventral zone of the epithelium, project to the ventral area of the bulb. A = anterior, P = posterior, M = medial, L = lateral, D = dorsal, and V = ventral