Fig. 4.

Model depicting development of the olfactory glomerular map along the D-V axis of the OB. At early stages of development, precursor cells within the DM region of the V-zone undergo high rates of cell proliferation, which increases the number of immature OSNs. A wave of cell proliferation travels along the D–V axis of the OE (top), from the DM- to VL-region. In accordance with the cell proliferation process, axon extension and glomerular formation occur sequentially, from the dorsal to ventral regions of the OB. The differential timing of OSN neurogenesis may define the timing of glomerular formation, thus contributing to the establishment of a precise olfactory glomerular map along the D–V axis (bottom)