Comparison of Lhx2 (A–E, J),Lhx9 (F–I, L), and En-2(K) expression on sections. A, F, Parasagittal adjacent sections through the entire brain at E14.5, comparing expression of Lhx2 (A) and Lhx9 (F). B, C, Coronal sections at E13.5 showing Lhx2 expression in the telencephalon and diencephalon. Sections are adjacent to those shown in Figure 3, B and E, respectively, for comparison of transverse boundaries. D, G, Horizontal adjacent sections showing Lhx2 (D) and Lhx9 (G) expression in the eye and optic stalk at E14.5. The asterisk inG points to the nonspecific signal attributable to the presence of the eye pigmented epithelium. E, H, Adjacent parasagittal section showing Lhx2(E) and Lhx9(H) in the dorsal diencephalon and pretectum at E13.5. Note the absence of Lhx2 in the pineal gland.I–K, Adjacent parasagittal sections at E13.5 to compareLhx9 (I),Lhx2 (J), and En-2(K) expression through the mesencephalon and metencephalon. Arrows in I andJ show the thinning of expression at the isthmus.L, Sagittal section through the midbrain of a P1 animal to show the Lhx9 sharp boundary between the superior and the inferior colliculi. Compare with I (earlier stage). Scale bars, 100 μm. ne, Nasal epithelium. See Table 1for abbreviations.