| CD4 cell count | The most commonly used surrogate marker for assessing the state of the immune system. As CD4 cell count declines, the risk of developing opportunistic infections increases. The normal range for CD4 cell counts is 500 to 1500 per cubic millimetre of blood. CD4 count should be rechecked at least every six to twelve months if CD4s are greater than 500/mm3. If the count is lower, testing every three months is advised. (09 Oct 1997) |
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| CD4 count, absolute | The number of helper T-lymphocytes in a cubic millimeter of blood. With HIV, the absolute CD4 count declines as the infection progresses. The absolute CD4 count is frequently used to monitor the extent of immune suppression in persons with HIV. Also called a T4 count. (12 Dec 1998) |
| CD4 lymphocyte count | A count of the number of CD4-positive lymphocytes in the blood. Determination requires the use of a fluorescence-activated flow cytometer. (12 Dec 1998) |
| cell count | A count of the number of cells of a specific kind, usually measured per unit volume of sample. (12 Dec 1998) |
| vitelline layer of egg | <zoology> The membrane, usually of protein fibres, immediately outside the plasmalemma of the ovum and the earlier stages of the developing embryo. Its structure and composition vary in differing animal groups. (18 Nov 1997) |
| centrolecithal egg | An egg in which the yolk is concentrated near the centre of the egg cell, as is the case in many of the insects. (05 Mar 2000) |
| reticulocyte count | Determination of the number of reticulocytes in a measured volume of blood. Values for reticulocytes are expressed as a percentage of the erythrocyte count or in the form of a so-called "corrected" reticulocyte "index". An increase in circulating reticulocytes, often referred to as reticulocytosis, is among the simplest and most reliable signs of accelerated erythrocyte production. Reticulocytosis, or an increased reticulocyte count, occurs during active blood regeneration (stimulation of red bone marrow) and in certain anaemias, particularly congenital haemolytic anaemia. (12 Dec 1998) |
| microlecithal egg | An egg containing a small amount of deutoplasm. (05 Mar 2000) |
| colony count, microbial | Enumeration by direct count of viable, isolated bacterial or fungal cells or spores capable of growth on solid culture media. Each colony (i.e., microbial colony-forming unit) represents the progeny of a single cell in the original inoculum. The method is used routinely by environmental microbiologists for quantifying organisms in air, food, and water; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing. (12 Dec 1998) |
| mosaic egg | <biology> At one time a distinction was drawn between those organisms in which the egg seemed to have a firmly committed fate map built in and regulating embryos. In the former, after the first cleavage one blastomere was committed to produce one set of tissues, the other blastomere a different set and removal of one blastomere led to the production of an incomplete embryo. This was particularly obvious in mollusc development where one blastomere had the polar lobe material. This early differentiation (or determination) of blastomeres for particular fates was in distinction to regulating embryos in which the removal of one blastomere did not matter, the other blastomere compensating and producing a full set of tissues. The distinction is, however, only based upon the timing of differentiative events and within a few divisions the regulating embryo also becomes a mosaic of determined cells. (18 Nov 1997) |
| white blood cell count | <haematology> A laboratory test which measures the number of white blood cells per cubic millimetre of blood. Normal white blood cell counts are variable with age and sex. Normal adult range is 4, 500 to 11,000 cells per cubic millimetre of blood. Slightly higher counts are seen in children. Elevated counts can be seen in cases of inflammation and infection. (13 Nov 1997) |
| complete blood count | <haematology, investigation> The number of red blood cells, white blood cells and platelets are present in the patients sample of blood is determined. most common test done on the blood. Acronym: CBC Synonym: full blood count. (16 Mar 1998) |
| platelet count | <haematology> The number of platelets per cubic millimetre of blood. The normal range is 150,000-400,000 platelets per cubic mm. Platelet counts under 10,000 per cubic millimetre place the patient at risk for spontaneous haemorrhage. Platelets are produced in the bone marrow in increased quantities in response to stress. (27 Sep 1997) |
| count | 1. A reckoning, enumeration, or accounting. 2. To enumerate or score. (05 Mar 2000) |
| count density | The number of counted events recorded in scintigraphy per square centimeter or per square inch of imaged area. Synonym: count density. (05 Mar 2000) |