Precocious neurogenesis and loss of sensory neurons in Rbpj -deficient DRG. (A-X) Transverse sections through the DRG of wild-type (WT) and Rbpj CKO mice for the indicated markers and counterstained with Hoechst at E10.5 (A-L), E11.5 (M-R) or E12.5 (S-X). At E10.5, Islet1/Sox10 double staining reveals an increase in the number of Islet1+ cells, but a decrease in that of Sox10+ cells in Rbpj-deficient DRG compared with wild-type controls (A-F). Note that many Islet1-expressing cells (arrows in A,D) are abnormally distributed in the upper portion of the Rbpj CKO DRG, a region normally occupied by Sox10+ cells (arrowheads in B,E) in wild-type DRG. At E11.5 (M-R), Sox10+ cells are distributed throughout wild-type DRG (asterisks in N), but are almost absent in the center of Rbpj-deficient DRG (asterisks in Q). At E12.5 (S-X), numbers of both Islet1+ and Sox10+ cells are reduced in Rbpj-deficient DRG compared with wild-type. (G-L) Double staining of Islet1 and NeuroD1 shows an increase in the number of NeuroD1+ cells in Rbpj-deficient DRG relative to wild-type controls at E10.5. Note that NeuroD1 and Islet are co-expressed in sensory neurons. Arrows in (G-K) point to the DRG. MN, motor neuron. Scale bars: 100 μm. (Y) Comparison of the number of Islet1+ or Sox10+ cells at the DRG between wild-type and Rbpj CKO mice at E10.5. Error bars represent standard error of the mean; *P < 0.01.