Carnegie Stage 11: Branchial Arches
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The notochord is a thin bar which extends along the length of the embryo. It is one of the first structures to develop and induces the growth of the neural tube. The neural tube is the embryo's future central nervous system (spinal cord and brain). Somites are unique segmented structures which form along the embryo's back (like beads on a string). They develop into most of the bones and muscles of the embryo as well as the skin of the back. Branchial arches are located in the throat area of the embryo. In fish, the branchial arches develop into gills, but in mammals (dolphins and humans) they contribute to the formation of the face and neck. The oropharynx is the precursor of the mouth and throat and is the beginning of the animal's gut tube.
