| tissue valve | A prosthetic cardiac valve derived from the pig heart, which is preserved and sterilised with glutaraldehyde, and permanently sutured to a shape-retaining artificial strut; in appropriate sizes, it can replace any natural heart valve. Synonym: porcine valve. (05 Mar 2000) |
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| tissue weighting factor | In radiation protection, a factor weighting the equivalent dose in a particular tissue or organ in terms of its relative contribution to the total deleterious effects resulting from uniform irradiation of the whole body. See: effective dose. (05 Mar 2000) |
| epithelial tissue | See: epithelium. (05 Mar 2000) |
| erectile tissue | A tissue with numerous vascular spaces that may become engorged with blood. Synonym: cavernous tissue. (05 Mar 2000) |
| fatty tissue | <anatomy> Connective tissue that has been specialised to store fat. See: adipocyte. (25 Jun 1999) |
| fibrin tissue adhesive | <chemical> An autologous or commercial tissue adhesive containing fibrinogen and thrombin. The commercial product is a two component system from human plasma that contains more than fibrinogen and thrombin. The first component contains highly concentrated fibrinogen, factor viii, fibronectin, and traces of other plasma proteins. The second component contains thrombin, calcium chloride, and antifibrinolytic agent such as aprotinin. Mixing of the two components promotes clotting and the formation and cross-linking of fibrin. The tissue adhesive is used for tissue sealing, haemostasis, and wound healing. Pharmacological action: haemostatics, tissue adhesives. (12 Dec 1998) |
| fibrohyaline tissue | In an adult, tissue resembling cartilage. In an embryo, an early stage in cartilage formation. Synonym: fibrohyaline tissue, pseudocartilage. (05 Mar 2000) |
| fibrous tissue | Although most connective tissue has fibrillar elements, the term usually refers to tissue laid down at a wound site well vascularised at first (granulation tissue) but later avascular and dominated by collagen rich extracellular matrix, forming a scar. Excessive contraction and hyperplasia leads to formation of a keloid. (18 Nov 1997) |
| foetal tissue transplantation | Transference of foetal tissue between individuals of the same species or between individuals of different species. (12 Dec 1998) |
| Lillie's allochrome connective tissue stain | <technique> A procedure using PAS, haematoxylin, picric acid, and methyl blue; used for distinction between basement membrane and reticulin, and for demonstration of arteriosclerotic lesions. (05 Mar 2000) |
| lymphatic tissue | A structure found within the lymphatic system that consists of lymphocytes within a network of fibres. (09 Oct 1997) |
| lymphoid tissue | <anatomy> Tissue that is particularly rich in lymphocytes (and accessory cells such as macrophages and reticular cells), particularly the lymph nodes, spleen, thymus, Peyer's patches, pharyngeal tonsils, adenoids and (in birds) the Bursa of Fabricius. Central lymphoid tissue: A term occasionally used as synonym for primary lymphoid tissue but should be avoided to prevent confusion between anatomical location, which is irrelevant and centrality in the system. Peripheral lymphoid tissue: Secondary lymphoid tissue, not necessarily located peripherally. Primary lymphoid tissue: Lymphoid tissues in which immune cells develop as opposed to the secondary or peripheral lymphoid tissues in which antigen independent or antigen dependent stages of maturation take place and in which responsive lymphocytes are found. Primary lymphoid tissues are foetal liver, adult bone marrow and thymus (and Bursa of Fabricius in birds). Secondary tissues are lymph nodes, spleen, tonsils and mucosa associated lymphoid tissue. (20 Mar 1998) |
| lymphoma, mucosa-associated lymphoid tissue | Extranodal lymphoma of lymphoid tissue associated with mucosa that is in contact with exogenous antigens. Many of the sites of these lymphomas, such as the stomach, salivary gland, and thyroid, are normally devoid of lymphoid tissue. They acquire malt tissue as a result of an immunologically mediated disorder. (12 Dec 1998) |
| acute reflex bone atrophy | Atrophy of bones, commonly of the carpal or tarsal bones, following a slight injury such as a sprain. See: causalgia, reflex sympathetic dystrophy. Synonym: acute reflex bone atrophy, posttraumatic osteoporosis, Sudeck's syndrome. Origin: L. English sweat (05 Mar 2000) |
| air-bone gap | The difference between the threshold for hearing acuity by bone conduction and by air conduction. (05 Mar 2000) |