Fig. 2. Olig3 is required to determine the fate of class A neurons in rhombomere 7. Immunohistological (A-F,I-P) and in situ hybridization (G,H) analyses of the alar plate of rhombomere 7 of control and Olig3 mutant mice at E11.5. (A,B) In control animals (A), Lbx1⁺ neurons were restricted to the ventral alar plate, and Lhx2/9⁺ neurons (dA1) arose at the dorsal lip. In Olig3 mutant mice (B), Lbx1⁺ neurons arose throughout the entire alar plate, and Lhx2/9⁺ neurons (dA1^*) co-expressed Lbx1. (C-F) Pax2 and Lhx1/5 (C,D) and Lbx1 and Pax2 (E,F) expression. (G,H) Analysis using a Gad1-specific probe. (I-P) Analyses using antibodies against Math1 (I,J), Ngn1 and Lhx1/5 (K,L), Ptf1a and Lhx1/5 (M,N) and Pax7 and Lbx1 (O,P). Note the expanded expression of Ptf1a in the Olig3 mutant mice. Distinct neuronal subtypes are indicated. Scale bars: 50 µm.