Somitomere

Somitomere is a term used in Embryology to describe the early divisions of the Mesoderm in the developing Embryo. These divisions, or segments, are the precursors to the Somites, which later give rise to important structures in the body such as the Vertebrae, Ribs, and part of the Skull.

Development

The process of somitomere formation begins during the third week of embryonic development. The Paraxial mesoderm, located on either side of the Neural tube, begins to segment into blocks. These blocks, or somitomeres, are initially spherical in shape and are not clearly separated from each other.

File:Somitomere.jpg

Somitomeres in a developing embryo

As development progresses, the somitomeres undergo a process of morphogenetic change, becoming more elongated and clearly separated. This process is regulated by a variety of genetic factors, including the Hox gene family and Notch signaling pathway.

Function

The somitomeres give rise to the somites, which are the building blocks of the Axial skeleton. Each somite will eventually differentiate into three parts: the Sclerotome, which forms the vertebrae and ribs; the Myotome, which forms the skeletal muscle; and the Dermatome, which forms the dermis of the skin.

In addition to their role in skeletal and muscular development, somitomeres also play a crucial role in the patterning of the Central nervous system. They are involved in the segmentation of the Rhombomeres, which are the building blocks of the Hindbrain.

See also

• Somite
• Mesoderm
• Embryogenesis
• Hox gene
• Notch signaling pathway