A group or layer of similarly specialized cells that together perform certain special functions. For anatomically specific tissues see under their identifying titles, e.g. adipose, connective.
- t. death — see necrosis.
- t. density — the penetrability of tissue by x-rays, bone and tooth being most dense, blood and soft tissue the next, fat the next, and gas and air least.
- t. edema — an abnormal accumulation of tissue fluid.
- t. factor — see tissue thromboplastin.
- t. fluid — the extracellular fluid that constitutes the environment of the body cells. It is low in protein, is formed by filtration through the capillaries, and the excess drains away as lymph. See also interstitial fluid.
- t. inhibitors — inhibitors of fibrinolysis; present in placenta.
- indifferent t. — undifferentiated embryonic tissue.
- t. necrosis fever — fever caused by pyrogens released by necrotic pyrogens.
- t. plasminogen activator — see plasminogen activator.
- t. reacting agent — substances that have a poorly defined but advantageous local effect on tissues.
- t. receptor site — a cell receptor common to cells of a particular tissue.
- t. residue — residues of chemical substances that are unacceptable to local pure food legislation especially sulfonamides, estrogens, chlorinated hydrocarbons, heavy metals. These are thought or known to have a deleterious effect on people eating or drinking the relevant animal product. See also chemical food residue.
- t. sensitivity — the susceptibility of individual tissues to injury by x-ray. The injury may be by way of inflammation, necrosis or cessation of cell growth. Fast-growing tissues in which the cells have a high mitotic index are the most sensitive, especially gonads, germinative layer of skin and erythropoietic tissues.
- supportive t's — cartilage and bone.
- t. therapy — see glandular therapy.
- t. typing — identification of tissue types for purposes of predicting acceptance or rejection of grafts and organ transplants. The process and purposes of tissue typing are essentially the same as for blood typing. The major difference lies in the kinds of antigens being evaluated. White blood cells, particularly lymphocytes, are used for tissue typing. The acceptance of allografts depends particularly on the matching of MHC antigens. If the donor and recipient are not MHC identical, the allograft is rejected. See also typing.
