FIG. 2.

Expression pattern of Sim2. In situ hybridization with ³⁵S-labeled Sim2 probe was used to assess the Sim2 expression pattern. Embryos were Carnoy's solution fixed, paraffin embedded, and sectioned at 8 μm. The histology of the sections is on the left next to the corresponding dark-field image revealing Sim2 expression (the silver granules). (A and A′) Midsagittal section of an E9.5 embryo. di, diencephalon. (B and B′) Transverse sections of an E10.5 embryo. (C and C′) Sagittal sections of an E10.5 embryo. sc, sclerotome; br, branchial arches; h, heart; lb, limb. (D and D′) Transverse sections of an E11.5 embryo. (E and E′) Sagittal sections of an E11.5 embryo. ar, vertebral arch; vb, vertebral body; r, ribs; L, lung; pw, pleural wall. (F and F′) Transverse sections of an E12.5 embryo. (G and G′) Sagittal sections of an E12.5 embryo. (L) Sagittal section of an E16.5 embryo. Sim2 shows expression in the PVN, kidney (k), muscles in the genital tubercles (gt), palate (p), nasal pit (np), tongue (t), ribs (r), vertebra (v), diaphragm (dia), and trachea (tr). st, sternum; H, heart. Higher magnifications of sagittal sections of E16.5 pleural cavity (H and H′) and diaphragm (K and K′) and transverse sections of vertebra and erector muscles (I and I′) and ribs (J and J′) are also shown. Arrowheads indicate Sim2-positive structures.