Fig. 6. Comparison of branchial motor neurons and regulatory gene expression domains. Branchial motor neurons (brown) are labeled in combination with LjKrox20 (A-C) or LjHox3 (D) expression domains (blue). (A) Lateral view of a stage 26 larva. (B) Dorsal view of the same larva. Note that the trigeminal (Vm) nucleus expands posteriorly into the LjKrox20-negative region, i.e. the presumptive r4 (white arrows). The facial (VIIm) nucleus also partially maps in the presumptive r4 domain (black arrow). (C) The glossopharyngeal motor (IXm) nucleus is just posterior to the r5 domain of LjKrox20. (D) The rostral boundary of LjHox3 expression maps between the Vm and VIIm nuclei. The inset clearly shows that the trigeminal motor nucleus is located just rostral to the LjHox3 expression domain.