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Figure 6. Semaphorin expression in the mesoderm and notochord at tadpole stages. In situ hybridization of the whole embryo (left), dashed line indicates the plane of the transverse section (right). A: Sema3A is expressed in the somites and the splanchnic mesoderm. B: Sema4B expression in the mesoderm is replaced by pronephros, cement gland, otic placode, proctodeum, spinal cord, and gut expression. C: Sema6B is expressed in the somites and otic placode at late neurula stages. D: At tadpole stages, the somite expression is limited to the dorsal and lateral margins of the somites (white arrow). E: Sema3F expression is detected in the notochord, but also in the spinal cord, the hypochord, the posterior endoderm, and the branchial arches. F: Sema4C notochord expression is replaced by expression in the posterior cardinal vein, the heart, and the branchial arches. G: Sema4D expression is detected in the notochord. H: Sema5B expression in the notochord is replaced by spinal cord, pronephros, brain, and eye expression. ba, branchial arches; cg, cement gland; en, endoderm; g, gut; h, heart; hc, hypochord; no, notochord; op, otic placode; p, pronephros; pcv, posterior cardinal vein; pd, proctodeum; s, somites; sc, spinal cord; sm, splanchnic mesoderm. |
