| null | 1. Something that has no force or meaning. 2. That which has no value; a cipher; zero. <physics> Null method, a zero method. See Zero. Source: Websters Dictionary (01 Mar 1998) |
|---|---|
| null cell | Lymphocytes lacking typical markers of T or B-cells capable of lysing a variety of tumour or virus infected cells without obvious antigenic stimulation, also effect antibody dependent cell cytotoxicity, carry in humans CD16 marker. (18 Nov 1997) |
| null cells | Large granular lymphocytes that lack surface markers/membrane associated proteins of either B or T lymphocytes. (05 Mar 2000) |
| null hypothesis | The assumption that any observed difference between two samples of a statistical population is purely accidental and not due to systematic causes. (05 Dec 1998) |
| null mutation | Change in a gene that leads to nothing, for example to no enzyme or to a nonfunctioning enzyme. (12 Dec 1998) |
| null-cell adenoma | <tumour> An adenoma of the hypophysis composed of cells for which there is no overt evidence or hormone production, but which usually produces hypopituitarism and visual disturbances by compression of adjacent structures; approximately one third of these tumours have cells with abundant mitochondria (oncocytes) that are somewhat larger than the monocytic null cells. Synonym: undifferentiated cell adenoma. (05 Mar 2000) |
| nulligravida | A woman who has never conceived a child. Origin: L. Nullus, none, + gravida, pregnant (05 Mar 2000) |
| nullipara | A woman who has not given birth to a viable child. (12 Dec 1998) |
| nulliparity | Never having carried a pregnancy. (27 Sep 1997) |
| nulliparous | Having never given birth to a viable infant. (18 Nov 1997) |
| nullipore | <botany> A name for certain crustaceous marine algae which secrete carbonate of lime on their surface, and were formerly thought to be of animal nature. They are now considered corallines of the genera Melobesia and Lithothamnion. Origin: L. Nullus none + porus pope. Source: Websters Dictionary (01 Mar 1998) |
| Rh null syndrome | <syndrome> A lack of all Rh antigens, compensated haemolytic anaemia, and stomatocytosis. (05 Mar 2000) |
|---|---|
| lymphocytes, null | A class of lymphocytes characterised by the lack of surface markers specific for either t or b lymphocytes. (12 Dec 1998) |