Schematic model and description of primary and established neurogenesis during mouse olfactory epithelium development. Coronal sections through heads at days 9.5–12.5 of gestation (e9.5–e12.5) are depicted for the phase of primary neurogenesis, while horizontal sections at e14.5 and e17.5 (immediately before birth) are portrayed for the phase of established neurogenesis. FB, forebrain; MNP, medial nasal process; VNO, vomeronasal organ; LNP, lateral nasal process; S, nasal septum; NC, nasal cavity. Adapted from Kawauchi S, Shou J, Santos R, et al. (2005) Fgf8 expression defines a morphogenetic center required for olfactory neurogenesis and nasal cavity development in the mouse. Development 132(23): 5211–5223.