Figure 8.

Lot cells, which are reduced in number in the Neurog1/2^−/− piriform cortex, are a subpopulation of CR cells. A–H, Labeling of E12.5 telencephalons from Neurog2^GFPKI+/− heterozygotes (“wild-type”; A, E), Neurog1^−/− mutants carrying one copy of the Neurog2^GFPKI allele (B, F), Neurog2^GFPKI/KI mutants (C, G), and Neurog1^−/−;Neurog2^GFPKI/KI double mutants (Neurog1/2^−/−; D, H) with anti-lot1 (A–D, red), anti-GFP (A–D, green), and a mGluR1 riboprobe (E–H). Insets in A–D are lot1 immunostaining of the lot. Arrows in D and H mark a loss of lot cells in the Neurog1/2^−/− piriform cortex. (I–L') Expression of lot1 in E15.5 wild-type (I, I'), Neurog1^−/− (J, J'), Neurog2^−/− (K, K'), and Neurog1/2^−/− (L, L') cortices. The images in I'–L' are high-magnification images of the boxed areas in I–L. M–P, Coexpression of lot1 (M, N′, red) and Reelin (N, N′, green), and of lot1 (O, P', red) and Trp73 (P, P') in the lot. Blue is DAPI counterstain in N′ and P'. Insets in N′ and P' are higher-magnification images of the lot. Q, Quantitation of the coexpression of lot1 with Reelin and Trp73. Cells that expressed high levels of lot1, which surround the LOT, were counted separately from those displaced from the lot (high and low lot⁺ cells, respectively). R, Schematic representation of E12.5 telencephalon, depicting the suggested dorsal pallial source of lot cells (red), and the cortical hem and ventral pallium as the sites of CR cell genesis (blue). S, Summary of our findings, demonstrating that Neurog1 and Neurog2 are coexpressed in dorsal and ventral pallial progenitors, which give rise to lot cells, a subset of Reelin⁺/Trp73⁺ CR cells. ch, Cortical hem; dp, dorsal pallium; lge, lateral ganglionic eminence; lot, lot guidepost cells; vp, ventral pallium.