Double in situ staining of mRNAs for down-regulated genes and Pax6 in the E11.5 rat hindbrain. The expression sites of Dbx1, Unc5h1 and Cyp26b1 (blue-violet in A-I and red in J-L) were compared with that of Pax6 (pink in A-I and blue in J-L) in WT (A, D, G, J), rSey2/+ (B, E, H, K) and rSey2/rSey2 (C, F, I, L) hindbrains in 'open-book' preparations. (A-C) Dbx1 expression is decreased throughout the interneuron progenitor domain of the rSey2/rSey2 hindbrain with the exception of r1, where Pax6 is not expressed (asterisk in C). (D-F) Unc5h1 expression disappears in the somatic motor neuron progenitor domain and in the dorsal region of r7 in the rSey2/rSey2 hindbrain (F). (G-L) Cyp26b1 expression is specifically altered in the dorsolateral region of r5 and r6 in the rSey2/rSey2 hindbrain (arrowheads in I and L). r1 to r7 indicate the individual rhombomeres of the hindbrain. Scale bar: 500 μm.