The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryonic stage of somitogenesis, along the head-to-tail axis in segmented animals.

Oct 20, 2010 · Somites are precursor populations of cells that give rise to important structures associated with the vertebrate body plan and will eventually differentiate into dermis, skeletal muscle, cartilage, tendons, and vertebrae. Somites also determine the migratory paths of neural crest cells and of the axons of spinal nerves.

As the primitive streak regresses and the neural folds begin to gather at the center of the embryo, the paraxial mesoderm separates into blocks of cells called somites. Although somites are transient structures, they are extremely important in organizing the segmental pattern of vertebrate embryos.

Somites are segmental units of the bilateral paraxial mesoderm (PM) lying lateral to the neural tube and notochord, and medial to the intermediate and lateral plate mesoderm. Dorsally, the somites are covered by surface ectoderm, and ventrally they are closely opposed to the endoderm and the aorta (Christ and Ordahl, 1995).

During development of vertebrate embryos, a series of repeated elements, called somites, is laid down on either side of the main axis of the body (neural tube and notochord) (for reviews see [1 – 4].

The term somitogenesis is used to describe the process of segmentation of the paraxial mesoderm within the trilaminar embryo body to form pairs of somites, or balls of mesoderm. In humans, the first somite pair appears at day 20 and adds caudally at 1 somite pair/90 minutes until on average 44 pairs eventually form.

Somitogenesis is the process by which somites form. Somites are bilaterally paired blocks of paraxial mesoderm that form along the anterior-posterior axis of the developing embryo in vertebrates. The somites give rise to skeletal muscle, cartilage, tendons, endothelium, and …

somite, in embryology, one of a longitudinal series of blocklike segments into which the mesoderm, the middle layer of tissue, on either side of the embryonic spine becomes divided. Collectively, the somites constitute the vertebral plate.

In the developing vertebrate embryo, somites are masses of mesoderm that can be found distributed along the two sides of the neural tube. They will eventually become dermis (dermatome), skeletal muscle (myotome), vertebrae (sclerotome), and …

Jan 9, 1998 · The most distinct feature of vertebrate mesodermal segmentation is the somite. Indeed, cell fate in the immature somite is flexible and dependent on local environmental signals.