Fig. 7. Non-melanogenic Kit⁺ cells in the head are not derived from Kit⁺ dorsal midline NT cells. (A) Dorsolateral view of a whole-mount E9.5 W^lacZ/+ embryo. ßgal⁺ cells are present in the branchial arches and presumptive cranial ganglia (filled arrows), and on roof plate (open arrow), but no ßgal⁺ cells emanate from the midbrain-hindbrain junction. (B) Transverse section through an E9.25 embryo at the midbrain-hindbrain junction, showing absence of ßgal⁺ cells on the dorsal midline and ectoderm. (C) Low-power view of a transverse section through the hindbrain region of an E10 W^lacZ/+ embryo at level of the trigeminal ganglion (boxed) stained for ßgal (green) and Isl1 (red). (D) High-power view of the boxed area in C, showing that many cells in the trigeminal ganglion are ßgal⁺/Isl1⁺ (yellow). (E) Transverse section through the caudal region of an E10.5 W^lacZ/+ embryo. Strong ßgal⁺ cells are present on roof plate, but completely absent in the dorsal neuroepithelium. Scale bars: 200 µm in A-C,E; 50 µm in D.