Fig. 5

Gli2 contributes to spinal motor neuron induction. Panels A–D show dorsal views, and panels E–L show lateral views of the hindbrain (E–J) and spinal cord (K and L), with anterior to the left. Asterisks in A–D indicate the position of the nIII and nIV motor neurons in the midbrain (A and B), and their absence (C and D). Arrowheads in A–D indicate the nV neurons in r2. (A and E) In control wild-type embryos, nk2.2 expression (E) and organization of cranial motor neurons (A) are identical to those described previously. (B and F) In gli2 MO-injected wild-type embryos, expression of nk2.2 (F) and development of cranial motor neurons (B) are identical to control embryos. (C and G) In control yot^ty119 mutants, the patterns of loss of nk2.2 expression (G) and cranial motor neurons (C) are similar to those described previously. (D and H) In gli2 MO-injected yot^ty119 mutants, nk2.2 expression is significantly restored in anterior rhombomeres and the caudal hindbrain (H, arrowheads). Concomitantly, the number of nV neurons (arrowhead) and nX neurons is significantly increased (D), and the pattern looks similar to that in control wild-type embryos. (I and K) In control dtr^te370 mutants, net1a is expressed at low levels in the ventral hindbrain, and at higher levels at rhombomere boundaries (I). In the mutant spinal cord (K), islet antibody-labeled motor neurons (arrowhead) are found in similar numbers to wild-type embryos. (J and L) In gli2 MO-injected dtr^te370 mutants, net1a expression in the hindbrain (J) shows no significant change (loss). In contrast, the number of motor neurons in the ventral spinal cord (arrowhead) is slightly but reproducibly reduced in MO-injected mutants (L).