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The epithelial–mesenchymal transition (EMT) is a process by which epithelial cells lose their cell polarity and cell–cell adhesion, and gain migratory and invasive properties to become mesenchymal stem cells; these are multipotent stromal cells that can differentiate into a variety of cell types.
During gastrulation, migrating epiblast cells undergo epithelial-mesenchymal transition in order to lose cell-cell adhesion , delaminate from the epiblast layer and migrate over the dorsal surface of the epiblast then down through the primitive streak. The first wave of epiblast cells to invaginate through the primitive streak invades and ...
Unlike epithelial cells – which are stationary and characterized by an apico-basal polarity with binding by a basal lamina, tight junctions, gap junctions, adherent junctions and expression of cell-cell adhesion markers such as E-cadherin, [4] mesenchymal cells do not make mature cell-cell contacts, can invade through the extracellular matrix, and express markers such as vimentin ...
In sea urchins, epithelial cells adhere to one another as well as the hyaline layer through classic cadherins and adherens junctions. Ingression is a very dynamic process however, and the first sign of an ingressing cell is seen when a future PMC loses its adhesion to hyaline, and cadherin, and increases its adhesion to a basal laminal substrate.
The first emergence of mesenchyme occurs during gastrulation from the epithelial–mesenchymal transition (EMT) process. This transition occurs through the loss of epithelial cadherin, tight junctions, and adherens junctions on the cell membranes of epithelial cells. [9]
The process controls the organized spatial distribution of cells during the embryonic development of an organism. Morphogenesis can take place also in a mature organism, such as in the normal maintenance of tissue by stem cells or in regeneration of tissues after damage. Cancer is an example of highly abnormal and pathological tissue morphogenesis.
This ingression sees the cells from the epiblast move into the primitive streak in an epithelial-mesenchymal transition; epithelial cells become mesenchymal stem cells, multipotent stromal cells that can differentiate into various cell types. The hypoblast is pushed out of the way and goes on to form the amnion. The epiblast keeps moving and ...
On day 16, epiblast cells that are next to the primitive streak experience epithelial-to-mesenchymal transformation as they ingress through the primitive streak. The first wave of epiblast cells takes over the hypoblast, which slowly becomes replaced by new cells that eventually constitute the definitive endoderm.