Fig. 1. Lhx1 and Lhx5 expression in the embryonic spinal cord. (A-F) In situ expression of Lhx1. (G-L) In situ expression of Lhx5. At E10.5 and E11.5, Lhx1 and Lhx5 are co-expressed in postmitotic neurons that correspond to dI2, dI4, dI6 and V0-V1 neurons (A,B,G,H). Lhx1 is also present in a subset of the motor neurons ventrally (arrow in B). Expression of Lhx1 and Lhx5 begins to diverge at E12.5 (C,I). Lhx1 is strongly expressed in the laterally located neurons (arrow in C), whereas Lhx5 is more strongly expressed in the subventricular zone where newborn dIL_A cells are emerging (arrow in I). By E13.5, the expression of Lhx1 and Lhx5 in the dorsal horn is largely complementary (D,J). Lhx1 persists in the dorsal horn (E,F; see arrow in E), whereas Lhx5 is downregulated at E14.5 (K) and is completely absent at E17.5 (L).