Somites

Somites are divisions of the body of an animal or embryo. In humans, they are the precursor structures to major body systems such as the vertebral column, dermis, and skeletal muscle. The process of somite formation, or somitogenesis, is a crucial aspect of early embryonic development.

Formation

Somites are formed from the mesoderm, one of the three primary germ layers in the very early embryo. The mesoderm is located between the endoderm and the ectoderm. The formation of somites is a process known as somitogenesis. This process begins with the formation of the notochord, which induces the overlying ectoderm to form the neural tube. The neural tube then signals the adjacent mesoderm to form into somites.

Structure

Each somite has a distinct structure, with a central area known as the myotome, which will eventually form the skeletal muscle. The outer layer of the somite, the dermatome, will form the dermis of the skin. The sclerotome, which forms the vertebrae and ribs, is located on the medial side of the somite, closest to the notochord.

Function

The somites give rise to important structures in the adult body. The myotome forms the skeletal muscles, the dermatome forms the dermis and subcutaneous tissue of the skin, and the sclerotome forms the vertebrae and the rib cage. In addition to these structures, the somites also play a crucial role in the segmentation of the body plan.

Clinical significance

Abnormalities in somite formation can lead to a range of medical conditions. For example, scoliosis can occur if the somites do not form correctly. Additionally, defects in somitogenesis can lead to conditions such as Klippel-Feil syndrome, which is characterized by the fusion of any two of the seven cervical vertebrae.

See also

• Embryogenesis
• Gastrulation
• Neurulation

References

Somites Resources
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