| null cells | Large granular lymphocytes that lack surface markers/membrane associated proteins of either B or T lymphocytes. (05 Mar 2000) |
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| Rh null syndrome | <syndrome> A lack of all Rh antigens, compensated haemolytic anaemia, and stomatocytosis. (05 Mar 2000) |
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| 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-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) |
| 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) |
| lymphocytes, null | A class of lymphocytes characterised by the lack of surface markers specific for either t or b lymphocytes. (12 Dec 1998) |
| absorptive cells of intestine | Cell's on the surface of villi of the small intestine and the luminal surface of the large intestine that are characterised by having microvilli on their free surface. (05 Mar 2000) |
| air cells | Air-containing spaces in the skull. See: pulmonary alveolus. (05 Mar 2000) |
| air cells of auditory tube | Occasional small air cells in the inferior wall of the auditory tube, near the tympanic orifice, communicating with the tympanic cavity. Synonym: cellulae pneumaticae tubae auditivae, air cells of auditory tube. (05 Mar 2000) |
| Alpha cells | Alpha cell's of pancreas or of anterior lobe of hypophysis. (05 Mar 2000) |
| alpha cells of anterior lobe of hypophysis | Acidophil cell's that constitute about 35% of the cell's of the anterior lobe. There are two varieties: one that elaborates somatotropin, another that elaborates prolactin. (05 Mar 2000) |
| alpha cells of pancreas | Cell's of the islets of Langerhans that secrete glucagon. (05 Mar 2000) |
| amniogenic cells | Cell's from which the amnion develops. (05 Mar 2000) |
| anabiotic cells | Cell's that are capable of resuscitation after apparent death; the existence of anabiotic tumour cell's is postulated to explain the recurrence of a cancer after a very long symptomless period following operation. (05 Mar 2000) |