| posterior perforated substance | The bottom of the interpeduncular fossa at the base of the midbrain, extending from the anterior border of the pons forward to the mamillary bodies, and containing numerous openings for the passage of perforating branches of the posterior cerebral arteries. Synonym: substantia perforata posterior, locus perforatus posticus, Malacarne's space. (05 Mar 2000) |
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| pressor substance | One of several products of intestinal putrefaction believed to cause functional hypertension when absorbed, any alkaline substance that raises blood pressure. Synonym: pressor amine, pressor substance. (05 Mar 2000) |
| proper substance | See: substantia propria of cornea, substantia propria membranae tympani, substantia propria sclerae. (05 Mar 2000) |
| schwann's white substance | <anatomy> The substance of the medullary sheath. Source: Websters Dictionary (01 Mar 1998) |
| psychoses, substance-induced | Psychotic organic mental disorders resulting from the toxic effect of drugs and chemicals or other harmful substance. (12 Dec 1998) |
| sensitizing substance | Antibody that combines with and sensitises antigen leading to the activation of complement, which may result in cell lysis. Synonym: CF antibody, sensitizing substance. (05 Mar 2000) |
| h substance | <haematology> A polysaccharide precursor molecule which is used to make the antigens on the surface of human blood cells that are classified in the ABO blood group system. (09 Oct 1997) |
| slow-reacting substance | Slow-reacting substance of anaphylaxis (SRS-A), a leukotriene of low molecular weight which is released in anaphylactic shock and produces slower and more prolonged contraction of muscle than does histamine; it is active in the presence of antihistamines (but not epinephrine) and seems not to occur preformed in mast cells, but as a result of an antigen-antibody reaction on the granules. Compare: peptidyl leukotrienes. Synonym: slow-reacting factor of anaphylaxis. (05 Mar 2000) |
| slow reacting substance of anaphylaxis | <immunology> Potent bronchoconstrictor and inflammatory agent released by mast cells, an important mediator of allergic bronchial asthma. A mixture of three leukotrienes (LTC4 mainly, LTD4 and LTE4) (18 Nov 1997) |
| soluble specific substance | A soluble type-specific polysaccharide produced during active growth of virulent pneumococci composing a large part of the capsule. Synonym: pneumococcal polysaccharide, soluble specific substance, specific soluble polysaccharide, specific soluble sugar. (05 Mar 2000) |
| specific capsular substance | A soluble type-specific polysaccharide produced during active growth of virulent pneumococci composing a large part of the capsule. Synonym: pneumococcal polysaccharide, soluble specific substance, specific soluble polysaccharide, specific soluble sugar. (05 Mar 2000) |
| spongy substance | Bone in which the spicules or trabeculae form a three-dimensional latticework (cancellus) with the interstices filled with embryonal connective tissue or bone marrow. Synonym: substantia trabecularis, cancellous bone, spongy bone, spongy substance, trabecular bone. (05 Mar 2000) |
| standard substance | A pure, authentic substance used for identification purposes. (05 Mar 2000) |
| Stilling's gelatinous substance | The central gray matter of the spinal cord surrounding the central canal. Synonym: substantia intermedia centralis et lateralis, anterior gray column, Stilling's gelatinous substance, substantia gelatinosa centralis. (05 Mar 2000) |
| neurosecretory substance | The secretion of nerve cell bodies located in the hypothalamus; the substance is transported by way of hypothalamo-hypophysial tract fibres into the neurohypophysis where the terminals of the nerve fibres contain the secretion. As seen in the fibres and terminals with a light microscope, the substance appears as Herring bodies or hyaline bodies of the pituitary (see under body). See: hyaline bodies of pituitary. (05 Mar 2000) |