| melanophage | A histiocyte that has phagocytised melanin. Origin: melano-+ G. Phagein, to eat (05 Mar 2000) |
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| melanophore | Cell type found in skin of lower vertebrates (amphibian skin, fish scales) that contains granules of the black pigment melanin. The granules can be rapidly redeployed between a dispersed state (which darkens the skin) and concentration at the centre (which lightens it). One of a family of pigmented or light diffracting, coloured cells, known collectively as chromatophores. (18 Nov 1997) |
| melanophore-expanding principle | A polypeptide hormone secreted by the intermediate lobe of the hypophysis in humans (in neurohypophysis in certain other species) which causes dispersion of melanin by melanophores, resulting in darkening of the skin, presumably by promoting melanin synthesis; this effect is readily demonstated in some lower vertebrates, such as frogs and fish; alpha-melanotropin is an N-acetylated peptide with 13 amino acids; beta-melanotropin has 22 amino acids. Synonym: intermedin, melanocyte-stimulating hormone, melanophore-expanding principle. (05 Mar 2000) |
| melanophores | Pigment cells containing melanin. (12 Dec 1998) |
| melanoplakia | The occurrence of pigmented patches on the tongue and buccal mucous membrane. Origin: melano-+ G. Plax, plate, plaque (05 Mar 2000) |
| melanoprotein | A protein complex containing melanin. (05 Mar 2000) |
| melanorrhagia | Synonym: melena. Origin: melano-+ G. Rhegnymi, to burst forth (05 Mar 2000) |
| melanorrhoea | <botany> An East Indian genus of large trees. Melanorrhoea usitatissima is the lignum-vitae of Peru, and yelds a valuable black varnish. Origin: NL, fr. Gr, black + to flow. Source: Websters Dictionary (01 Mar 1998) |
| melanoscope | <instrument, optics> An instrument containing a combination of coloured glasses such that they transmit only red light, so that objects of other colours, as green leaves, appear black when seen through it. It is used for viewing coloured flames, to detect the presence of potassium, lithium, etc, by the red light which they emit. Origin: Gr, black + -scope. Source: Websters Dictionary (01 Mar 1998) |
| melanosis | A disorder caused by a disturbance in melanin pigmentation, melanism. (18 Nov 1997) |
| melanosis circumscripta precancerosa | An obsolete term for lentigo maligna. (05 Mar 2000) |
| melanosis coli | Melanosis of the large intestinal mucosa due to accumulation of pigment of uncertain composition within macrophages in the lamina propria. (05 Mar 2000) |
| melanosis corii degenerativa | A congenital abnormality in which pigment is deposited in whorls and streaks; vesicles occasionally occur, and it may be associated with cardiac or neurologic disorders. Compare: incontinentia pigmenti, incontinentia pigmenti achromians. (05 Mar 2000) |
| melanosity | Darkness of complexion. (05 Mar 2000) |
| melanosome | <cell biology> Membrane bounded organelle found in melanocytes, when melanin synthesis is active internal structure is characteristic, containing melanofilaments that have a periodicity of around 9nm and are arranged in parallel arrays. Mature melanosomes, in which the filamentous structure is masked by the dense accumulation of melanin, are transferred to keratinocytes. Origin: Gr. Soma = body (13 Nov 1997) |