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Functions of epithelial tissue: The principle function of epithelial tissues are covering and lining of free surface; The cells of the body's surface form the outer layer of skin. Inside the body, epithelial cells form the lining of the mouth and alimentary canal and protect these organs. Epithelial tissues help in the elimination of waste.
Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial (mesothelial) tissues line the outer surfaces of many internal organs, the corresponding inner surfaces of body cavities, and the inner surfaces of blood vessels.
Subsets of sensory intestinal epithelial cells synapse with nerves, [9] and are known as neuropod cells. [10] Paneth cells produce antimicrobial peptides such as human alpha-defensin. [11] [12] Microfold cells (commonly referred to as M cells) sample antigens from the lumen and deliver them to the lymphoid tissue associated with the mucosa (MALT).
Goblet cells are simple columnar epithelial cells, having a height of four times that of their width. The cytoplasm of goblet cells tends to be displaced toward the basal end of the cell body by the large mucin granules, which accumulate near the apical surface of the cell along the Golgi apparatus, which lies between the granules and the nucleus.
In 1989, two scientific groups came up with the hypothesis that the thymus expresses genes which are in the periphery, strictly expressed by specific tissues (e.g.: Insulin produced by β cells of the pancreas) to subsequently present these so-called "tissue-restricted antigens" (TRAs) from almost all parts of the body to developing T cells in order to test which TCRs recognize self-tissues ...
The cells in the respiratory epithelium are of five main types: a) ciliated cells, b) goblet cells, c) brush cells, d) airway basal cells, and e) small granule cells (NDES) [6] Goblet cells become increasingly fewer further down the respiratory tree until they are absent in the terminal bronchioles; club cells take over their role to some extent here. [7]
It can spread to the tissues and fat surrounding the kidney, the fat surrounding the ureter, or, more progressively, lymph nodes and other organs, including bone. Common risk factors of transitional cell carcinoma include long-term misuse of pain medication, smoking, and exposure to chemicals used in the making of leather, plastic, textiles ...
Other kinds of connective tissues include fibrous, elastic, and lymphoid connective tissues. [11] Fibroareolar tissue is a mix of fibrous and areolar tissue. [12] Fibromuscular tissue is made up of fibrous tissue and muscular tissue. New vascularised connective tissue that forms in the process of wound healing is termed granulation tissue. [13]