In normal early embryonic development, the outer epithelial layer contains cytotrophoblast cells, a stem cell type found in the trophoblast that later differentiates into the fetal placenta.
22.
The cells comprising an epithelial layer are linked via semi-permeable, tight junctions; hence, this tissue provides a barrier between the external environment and the organ it covers.
23.
The normal epithelium abruptly transitions into a narrow zone of rapidly thickening epithelial layers, made up of rapidly multiplying cells ( Shope et al . 1933 ).
24.
Studies using the electron microscope showed that the electrical resistance of epithelial layers depends on the complexity and number of filaments within the tight junction transmembrane protein complexes.
25.
"' Podocytes "'are epithelial layers, the name "'visceral epithelial cells "'usually refers specifically to podocytes, which are specialized epithelial cells that reside in the visceral layer of the capsule.
26.
One proposed mechanism is that tuberculous infection in the lungs results in erosion of the epithelial layer of alveolar cells and the spread of infection into a pulmonary vein.
27.
The back surface is covered by a heavily pigmented epithelial layer that is two cells thick ( the iris pigment epithelium ), but the front surface has no epithelium.
28.
These complexes, which help regulate cell growth in addition to creating and maintaining epithelial layers, are known as adherens junctions and they typically include at least cadherin, ?-catenin, and ?-catenin.
29.
Cortactin is activated via phosphorylation, by tyrosine kinases or serine / threonine kinases, in response to extracellular signals like growth factors, adhesion sites, or pathogenic invasion of the epithelial layer.
30.
The back surface is covered by a commonly, heavily pigmented epithelial layer that is two cells thick ( the iris pigment epithelium ), but the front surface has no epithelium.
