Skin and musculature

The skin and its appendages

Following development of the nervous system, the ectoderm becomes subdivided into neuroectoderm (neural groove and neural tube) and surface ectoderm. After the closure of the neural tube, the surface ectoderm covers the embryo up to the transition into the amnion (sulcus amnio-embryonicus). As the nervous system grows, the embryo bends forward at its cranial and caudal ends. This transition from surface ectoderm to amnion becomes narrowed towards the umbilical ring.