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The dermatome is the dorsal portion of the paraxial mesoderm somite which gives rise to the skin . In the human embryo, it arises in the third week of embryogenesis. [2] It is formed when a dermomyotome (the remaining part of the somite left when the sclerotome migrates), splits to form the dermatome and the myotome. [2]
Once cells have adopted somite fate they undergo an epithelial-mesenchymal transition and form a new somite. [11] The position of the somite boundary is thought to be controlled by a gradient of FGF or Wnt signalling that moves posteriorly at the rate that the embryo elongates and grows [3], thus coupling somite size to the size of the embryo ...
Internal anatomy of a female - 1 o-slit shaped orifice of poison gland. Behind the mouth opening is a mandible with a 5 segmented palpus. a-anus. s-are the two column-shaped spiracles leading into the lungs or tracheae. s'-is an unpaired spiracle that leads into tubular tracheae. The abdomen has the intestine and ovary embedded in the liver.
The morphogenic rearrangement of somites into dermamyotome formed from the dorsal part of the somite and sclerotome happens while maintaining the segmental pattern. Dermamyotome, which retains the epithelial properties of its origin, forms the dermis and skeletal muscle, while sclerotome gives rise to the vertebral column and ribs.
The anatomical term myotome which describes the muscles served by a spinal nerve root, is also used in embryology to describe that part of the somite which develops into the muscles. [3] In anatomy the myotome is the motor equivalent of a dermatome .
The term is also used to refer to a part of an embryonic somite. Along the thorax and abdomen, the dermatomes are like a stack of discs forming a human, each supplied by a different spinal nerve. Along the arms and the legs, the pattern is different: the dermatomes run longitudinally along the limbs.
Many kinds of tissue derive from the segmented paraxial mesoderm by means of the somite. Among these are: the sclerotome, which forms cartilage, the syndetome, which forms tendons, the Myotome, which forms skeletal muscle, the dermatome, which forms the dermis as well as skeletal muscle, and endothelial cells.
The folding of the neural tube to form an actual tube does not occur all at once. Instead, it begins approximately at the level of the fourth somite at Carnegie stage 9 (around embryonic day 20 in humans). The lateral edges of the neural plate touch in the midline and join together.