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Epithelial cell specialization


The cells of epithelial tissues remain attached to each other by specialized structures, generally called cell junctions.

Note these junctions in the figure below.

Desmosomes

One of the most important cell junctions is the desmosome (from the Greek desmos, bond, and sums, body). A demosome can be compared to a pushbutton consisting of two halves that snap together, one half located on the membrane of one cell and the other in the neighboring cell.

In each cell there is a circular protein plate, situated right next to the membrane. From the plates, sticky substances called desmelinins pass through the membranes and stick to the cells in the contact region. Plates are also attached to a large number of keratin protein filaments.


Electron microscopy of cell showing circular plate