Tissue growth

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Cell growth, division & proliferation

Tissue growth is the process by which a tissue increases its size. In animals, tissue growth occurs during

tissue regeneration. The fundamental cellular basis for tissue growth is the process of cell proliferation, which involves both cell growth and cell division occurring in parallel.[1][2][3][4]

How cell proliferation is controlled during tissue growth to determine final tissue size is an open question in biology. Uncontrolled tissue growth is a cause of cancer.

Differential rates of cell proliferation within an organ can influence proportions, as can the orientation of cell divisions, and thus tissue growth contributes to shaping tissues along with other mechanisms of tissue morphogenesis.

Mechanisms of tissue growth control in animals

Mechanical control of tissue growth in animal skin

For some animal tissues, such as mammalian

differentiating
supra-basal daughter cells.

transcription factors in the nucleus to activate target gene expression and thereby drive cell proliferation
.

For other animal tissues, such as the bones of the

gene regulatory networks encoded in the genome
lead to organs of such different sizes and proportions.

Hormonal control of tissue growth in the entire animal body

Although different animal tissues grow at different rates and produce organs of very different proportions, the overall growth rate of the entire animal body can be modulated by circulating hormones of the

giantism while insufficient production of these hormones is responsible for dwarfism
.

Developmental control of tissue growth during adult tissue homeostasis

Adult animal tissues such as

stem cells and progenitor cells while undergoing an equivalent loss of differentiated daughter cells via sloughing off. Gradients of Wnt signaling pathway
activity appear to have a fundamental role in maintaining proliferation of stem and progenitor cells, at least in the intestine, and possibly also in skin.

Regenerative tissue growth after wounding or other types of damage

Upon tissue damage, there is an upregulation in the activity of many pathways that control tissue growth, including the

growth factors that activate the PI3K/AKT/mTOR pathway
.

References

  1. S2CID 15738174
    .
  2. PMID 12733996
    .
  3. S2CID 14608744
    .
  4. PMID 20833011
    .
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