axis elongation involved in somitogenesis

Definition

Target type: biologicalprocess

The developmental growth that results in the elongation of the rostral-caudal axis that contributes to somitogenesis. [GOC:ascb_2009, GOC:dph, GOC:tb]

Somitogenesis is a crucial developmental process that generates segmented blocks of mesoderm called somites, which give rise to vertebrae, ribs, muscles, and dermis. Axis elongation is an integral aspect of somitogenesis, contributing to the formation of the body axis. This process involves a series of coordinated events, including:

1. **Segmentation Clock:** A molecular oscillator within the presomitic mesoderm (PSM) generates cyclic expression patterns of genes like Hes7 and Lunatic Fringe, creating a temporal wavefront that defines the boundaries of each future somite.

2. **Somite Formation:** The PSM is progressively patterned, with cells at the anterior edge of the wavefront gaining competence to form a somite. This competence is driven by signals from the neighboring tissues, including retinoic acid from the posterior region and Wnt signals from the anterior region.

3. **Axis Elongation:** As somites form, the PSM itself is progressively elongated. This elongation is crucial for maintaining a sufficient pool of cells to continue generating new somites.

4. **Cell Migration and Proliferation:** Axis elongation involves a complex interplay of cell movements and proliferation. Cells at the tailbud, the most posterior region of the PSM, contribute to the growth of the axis by migrating anteriorly and differentiating into PSM cells. This process requires the coordinated action of signaling pathways, including Wnt and FGF.

5. **Epithelial-Mesenchymal Transition (EMT):** During somite formation, mesenchymal cells from the PSM undergo EMT to form the epithelial somite boundary. This process involves changes in cell adhesion and cytoskeletal organization, contributing to the compaction and segregation of somites.

6. **Fibroblast Growth Factor (FGF) Signaling:** FGF signaling is essential for both axis elongation and somite formation. FGFs from the tailbud and posterior PSM promote cell proliferation and migration, contributing to the lengthening of the body axis.

7. **Wnt Signaling:** Wnt signals from the anterior PSM are essential for somite boundary formation and the establishment of anterior-posterior polarity within the somites. They also contribute to the regulation of cell proliferation and differentiation in the PSM.

8. **Retinoic Acid (RA) Signaling:** Retinoic acid from the posterior region of the embryo establishes the anterior-posterior polarity of the PSM and influences the timing of somite formation. It also plays a role in regulating the expression of genes involved in axis elongation.

9. **Other Signaling Pathways:** Several other signaling pathways, including Notch, TGFβ, and Shh, also contribute to the regulation of axis elongation and somite formation.

In summary, axis elongation during somitogenesis is a tightly regulated process that involves the coordination of multiple signaling pathways, cell movements, and changes in gene expression. This dynamic process ensures the formation of a segmented body axis, essential for the development of the vertebral column, ribs, muscles, and other structures.'
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Compounds (3)