We’re not sure. From ScienceDaily:
As cells divide to form tissues and organs in multicell organisms, they move to where they belong, informed by a series of cues that scientists have yet to observe or fully understand.
These collective movements traditionally have been studied in the context of biochemical recognition between cell types. For example, the protein cadherin (found in, and named for, calcium dependent adhesions) is one element responsible for cells’ ability to recognize one another, with various types of cadherin occurring at different sites in the organism. These cadherin receptors enable like cells to combine with each other to build specific types of tissue; for example, E-cadherin is so named because it is found in epithelial cells.
“Cadherins provide an initial signal for the ‘handshake’ between cells, but they are not the primary keeper of the connection,” says UC Santa Barbara professor and mechanical engineer Beth Pruitt, who studies mechanobiology and is working to gain a greater understanding of how cells combine to form tissues and maintain their integrity under the normal loads they experience …
As cells slide past each other while migrating toward their destinations during development or wound healing, they exert shear forces. Exactly how these local in-plane shear forces are spread throughout a tissue — important in collective tissue behavior — is not understood, in part because it is difficult to apply direct, localized shear within a tissue…
“Through observing these oscillations and measuring overall forces, as enabled by the inline spring, we were able to put forward a mechanical model that includes a mechanical signal-storage-and-relay element for simulating epithelial cell monolayers,” Pruitt explained. “This element, in parallel with the cells’ well-known viscoelastic property, can account for the collective behavior we observed. Cells might utilize this behavior following a shear-induced force imbalance to maintain tension homeostasis within a developing tissue.” Paper. (open access) – Ehsan Sadeghipour, Miguel A Garcia, William James Nelson, Beth L Pruitt. Shear-induced damped oscillations in an epithelium depend on actomyosin contraction and E-cadherin cell adhesion. eLife, 2018; 7 DOI: 10.7554/eLife.39640 More.
While the researchers don’t, of course, come right out and say this, massive communications exist within each cell, whether of a mouse, a grapevine, or a human. And we really don’t know very much about it at all. Yet many presume to insist that such structures arose randomly as a result of natural selection acting on random mutation (Darwinism), which cannot possibly be true. If it were, strange things would be happening all over the place. Yet they are not.
Is it just imagination or do people increasingly write in such a way as to simply abandon the pretense without wanting to discuss it?
See also: Researchers A Kill Cancer Code Is Embedded in Every Cell
How Do Cells Interpret The “Dizzying” Communications Pathways In Multicellular Life Forms?
Cell atlases reveal extreme complexity at biology’s frontiers
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