somite development

Definition

Target type: biologicalprocess

The progression of a somite from its initial formation to the mature structure. Somites are mesodermal clusters that are arranged segmentally along the anterior posterior axis of an embryo. [GOC:dph]

Somite development is a fundamental process in vertebrate embryogenesis, responsible for generating the segmented blocks of mesoderm that give rise to skeletal muscles, vertebrae, and dermis. This intricate process involves a series of precisely coordinated steps:

1. **Formation of the presomitic mesoderm (PSM):** The PSM, located anterior to the forming somites, is a dynamic pool of mesodermal cells that constantly migrate and proliferate.

2. **Segmentation of the PSM:** The PSM undergoes rhythmic segmentation, forming periodic structures called somites. This segmentation is driven by a complex interplay of molecular signaling pathways, including Notch, Wnt, and FGF. The expression of these signaling molecules creates oscillating gradients within the PSM, leading to the formation of somite boundaries.

3. **Somite morphogenesis:** Each somite differentiates into distinct regions:

* **Sclerotome:** The ventromedial region gives rise to the vertebrae and ribs.
* **Myotome:** The dorsolateral region develops into skeletal muscles.
* **Dermatome:** The dorsal region forms the dermis of the skin.

4. **Somite differentiation:** The process of somite formation is tightly linked to the establishment of cell fate within the somite. This involves:

* **Myogenesis:** Myotome cells differentiate into myoblasts, which fuse to form muscle fibers.
* **Chondrogenesis:** Sclerotome cells differentiate into chondrocytes, responsible for forming cartilage that ultimately forms bone.
* **Dermatogenesis:** Dermatome cells form the dermal layer of the skin.

5. **Somite boundary formation:** Somite boundaries are crucial for proper segmentation and the formation of distinct structures. These boundaries are established by the expression of specific genes, such as Ephrins and their receptors, which ensure cell adhesion and prevent cell mixing between adjacent somites.

6. **Somite maturation:** After their initial formation, somites undergo further maturation and refinement, contributing to the development of the axial skeleton, muscles, and skin.

The precise timing and coordination of these molecular events and cellular interactions are crucial for the proper development of the body axis and the formation of functional tissues. Disruptions in somite development can lead to severe congenital malformations.'
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Proteins (4)

Compounds (22)