Normal expression of 5-HT, TPH, Sert, Lmx1b, and Pet1 in the rostral part of the hindbrain of Lmx1bf/f/p mice and wild-type (WT) mice. A, B, 5-HT expression detected by immunocytochemical staining in Lmx1bf/f/p mice (B, arrow) was similar compared with Lmx1bf/+/p mice (A, arrow) at E11. C, D, Normal expression of TPH detected by immunocytochemical staining in Lmx1bf/f/p mice (D, arrow) compared with the control (C, arrow) at E11. E–J, Expression of Sert, Lmx1b, and Pet1 detected by in situ hybridization was indistinguishable in Lmx1bf/f/p mice (F, H, J, arrows) compared with wild-type mice (E, G, I, arrows). fp, Floor plate. Scale bars: D, 100 μm; J, 200 μm.