Epithelium

Epithelium

Types of epytheliums

The epithelia are tissues made from cells closely juxtaposed, without the interposition of fiber or ground substance (which distinguishes them from connective tissue). The cells are linked to each other through intercellular junctions. They are not vascularisés with the exception of vascular streaks (cochlea, the production of endolymph). The input of nutrients and export of waste is done in conjunction with connective tissue underlying through a basement membrane, which rests epithelium (if a fabric has joined cells but not basal, this is not an epithelium, such épendymocytes). In this type of tissue, cells are often polarized (the two opposite ends are different morphologically and biochemically), although there are some epithelia where this polarity is difficult to distinguish (liver tissue). There are the apical region of the cell and basal region which is attached to the basal lamina.

They meet two physiological functions not exclusive of each other: function coating and glandular function.

The presence of specific intermediate filament Cytokeratin allows their identification by immunohistochemical methods.