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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]
[4] [5] However, the segmentation clock model is highly evolutionarily conserved. [ 6 ] Intrinsic expression of "clock genes" must oscillate with a periodicity equal to the time necessary for one somite to form, for example 30 minutes in zebrafish, 90 minutes in chicks, and 100 minutes in snakes.
A dermatome is an area of skin that is mainly supplied by afferent nerve fibres from the dorsal root of any given spinal nerve. [ 1 ] [ 2 ] There are 8 cervical nerves (C1 being an exception with no dermatome), 12 thoracic nerves , 5 lumbar nerves and 5 sacral nerves .
As a matter of fact, these inhibitory chemicals expressed in the posterior sclerotome forms the basis of the segmentation pattern observed in the vertebrate nervous system. [12] In short, the segmental arrangement of the peripheral nervous system (PNS) seen in vertebrates derives from the division of the sclerotomes into anterior and posterior ...
It is thought that early scleraxis-expressing progenitor cells lead to the eventual formation of tendon tissue and other muscle attachments. [1] Scleraxis is involved in mesoderm formation and is expressed in the syndetome (a collection of embryonic tissue that develops into tendon and blood vessels) of developing somites (primitive segments or compartments of embryos).
Here, retinoic acid interacts with these pathways. [6] Early markers of somites exist but are not expressed in cephalic mesoderm, although the same cell types that are generated in somites are generated in cephalic mesoderm, such as angioblasts , myocytes , and a variety of connective tissues.
The peripheral nervous system (PNS) is divided into the somatic nervous system, the autonomic nervous system, and the enteric nervous system.However, it is the somatic nervous system, responsible for body movement and the reception of external stimuli, which allows one to understand how cutaneous innervation is made possible by the action of specific sensory fibers located on the skin, as well ...
In the fifth week, there are 4 occipital somites, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 8 to 10 coccygeal that will form the axial skeleton. Somitic derivatives are determined by local signaling between adjacent embryonic tissues, in particular the neural tube, notochord, surface ectoderm and the somitic compartments themselves. [ 8 ]