| polymorph | <chemistry> A substance capable of crystallizing in several distinct forms; also, any one of these forms. Cf. Allomorph. Origin: Gr. Multiform; many + form: cf. F. Polymorphe. Source: Websters Dictionary (01 Mar 1998) |
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| polymorphic | <biology> Occurring in several or many forms, appearing in different forms at different stages of development. Origin: Gr. Morph = form (18 Nov 1997) |
| polymorphic epithelial mucin | <protein> See episialin. (18 Nov 1997) |
| polymorphic genetic markers | Inherited characteristics that occur within a given population as two or more traits. (05 Mar 2000) |
| polymorphic leaves | Two or more different types of leaves on plants, in wetland plants, polymorphic leaves may develop due to extended flooding. (09 Oct 1997) |
| polymorphic neuron | Occurring in many shapes. See: multipolar cell. (05 Mar 2000) |
| polymorphic reticulosis | A necrotizing lymphoproliferative lesion with a predilection for the upper respiratory tract. Previously called lethal midline granuloma or malignant midline reticulosis. Treatment is irradiation. (05 Mar 2000) |
| polymorphic superficial keratitis | Epithelial degeneration occurring in starvation. (05 Mar 2000) |
| polymorphism | 1. <genetics> The regular and simultaneous occurrence in a single interbreeding population of two or more alleles of a gene, where the frequency of the rarer alleles is greater than can be explained by recurrent mutation alone (typically greater than 1%). The concept includes chromosome polymorphism. HLA alleles of the major histocompatibility complex are very polymorphic. 2. <zoology> The differentiation of various parts of the units of colonial animals into different types of unit specialised for different purposes, for example as in the colonial hydroid Obelia. (04 Jul 1999) |
| polymorphism, single-stranded conformational | Variation occurring within a species in the conformation of denatured DNA fragments. These single-stranded DNA fragments are allowed to partially renature in a way that prevents the formation of double-stranded DNA. The fragments are run on polyacrylamide gels under various conditions to detect subtle changes in migration due to altered secondary structure. The resulting bands will align themselves if the fragments are the same, but will misalign if any point mutations are present. Sscps have been used in detecting mutations in various genes, such as oncogenes, tumour suppressor genes, and genes responsible for genetic diseases. (12 Dec 1998) |
| polymorphocellular | Relating to or formed of cells of several different kinds. Origin: G. Polymorphos, multiform, + L. Cellula, cell (05 Mar 2000) |
| polymorphocytic leukaemia | Granulocytic leukaemia, especially any variety in which the predominant cells are mature, segmented granulocytes. (05 Mar 2000) |
| polymorphonuclear | Having nuclei of varied forms; denoting a variety of leukocyte. Origin: G. Polymorphos, multiform, + L. Nucleus, kernel (05 Mar 2000) |
| polymorphonuclear leucocyte | Mammalian blood leucocyte (granulocyte) of myeloid series in distinction to mononuclear leucocytes: See: neutrophil, eosinophil, basophil. (18 Nov 1997) |
| polymorphonuclear leukocyte | Small, actively motile white blood cells containing many lysosomes and specialising in phagocytosis. (09 Oct 1997) |