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Epithelial polarity is one example of the cell polarity that is a fundamental feature of many types of cells. Epithelial cells feature distinct 'apical', 'lateral' and 'basal' plasma membrane domains. Epithelial cells connect to one another via their lateral membranes to form epithelial sheets that line cavities and surfaces throughout the ...
Epithelial cells also exhibit planar cell polarity, in which specialized structures are orientated within the plane of the epithelial sheet. Some examples of planar cell polarity include the scales of fish being oriented in the same direction and similarly the feathers of birds, the fur of mammals, and the cuticular projections (sensory hairs ...
[21] [22] This mechanism activates the neoblasts which are totipotent stems cells [23] which allows rhabdites to secrete materials to make a protective mucosal covering and epithelium to gather at the site through spreading of the cells rather than proliferation that occurs in vertebrates [22] The dorsal and ventral epithelial cells then come ...
Cells first need to establish a polarity through a symmetry-breaking event before tissues and organs themselves can be polar. For example, one model proposes that left-right body axis asymmetry in vertebrates is determined by asymmetry of cilia rotation during early development, which will produce a constant, unidirectional flow.
Morphogenesis is essential for the evolution of new forms. Morphogenesis is a mechanical process involving forces that generate mechanical stress, strain, and movement of cells, [1] and can be induced by genetic programs according to the spatial patterning of cells within tissues. Abnormal morphogenesis is called dysmorphogenesis.
In morphogenesis, apical constriction is the process in which contraction of the apical side of a cell causes the cell to take on a wedged shape. Generally, this shape change is coordinated across many cells of an epithelial layer, generating forces that can bend or fold the cell sheet. [1]
Neuroepithelial cells give rise to radial glial progenitor cells in early embryonic development. To make this change, neuroepithelial cells begin to downregulate their epithelial features, by stopping the expression of occludin, a tight junction protein. [3]
The differentiation phase of the Induction stage is initiated by the presence of newly formed predentin. The IEE cells then elongate and become preameloblasts. There is a shift in polarity. Each preameloblast elongates and becomes an postmitotic, polarized, secretory ameloblast. However, there are no Tomes' process yet.