| 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) |
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| 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) |
| alveolar dead space | The difference between physiologic dead space and anatomical dead space; it represents that part of the physiologic dead space resulting from ventilation of relatively underperfused or nonperfused alveoli; it differs specifically in being placed so as to fill and empty in parallel with functional alveoli, rather than being interposed in the conducting tubes between functional alveoli and the external environment. (05 Mar 2000) |
| anatomical dead space | The volume of the conducting airways from the external environment (at the nose and mouth) down to the level at which inspired gas exchanges oxygen and carbon dioxide with pulmonary capillary blood; formerly presumed to extend down to the beginning of alveolar epithelium in the respiratory bronchioles, but more recent evidence indicates that effective gas exchange extends some distance up the thicker-walled conducting airways because of rapid longitudinal mixing. Compare: alveolar dead space, physiologic dead space. Synonym: anatomical airway. (05 Mar 2000) |
| antecubital space | The fossa in front of the elbow, bounded laterally and medially by the humeral origins of the extensors and flexors of the forearm, respectively, and superiorly by an imaginary line connecting the humeral condyles. Synonym: fossa cubitalis, antecubital space, chelidon, triangle of elbow. (05 Mar 2000) |
| anterior clear space | On lateral chest radiographs, the region dorsal to the sternum and ventral to the ascending aorta. Synonym: anterior clear space. (05 Mar 2000) |
| apical space | The space between the alveolar wall and the apex of the root of a tooth where an alveolar abscess usually has its origin. (05 Mar 2000) |
| axillary space | <anatomy> The underarm area. (16 Dec 1997) |
| Berger's space | The space between the patellar fossa of the vitreous and the lens. (05 Mar 2000) |
| Bogros' space | A triangular space between the peritoneum and the transversalis fascia, at the lower angle of which is the inguinal ligament; it contains the lower portion of the external iliac artery. Synonym: Bogros' space, spatium retroinguinale. (05 Mar 2000) |
| Bottcher's space | The blind pouch at the end of the endolymphatic duct. (12 Dec 1998) |
| Bowman's space | The slitlike space between the visceral and parietal layers of the capsule of the renal corpuscle; it opens into the proximal tubule of the nephron at the neck of the tubule. Synonym: Bowman's space, filtration space. (05 Mar 2000) |
| Burns' space | A narrow interval between the deep and superficial layers of the cervical fascia above the manubrium of the sternum through which pass the anterior jugular veins. Synonym: Burns' space. (05 Mar 2000) |