| colony-forming unit | <cell biology> An individual cell which is able to clone itself into an entire colony of identical cells. Irradiated mice can have their immune systems reconstituted by the injection of bone marrow cells from a nonirradiated animal. The injected cells form colonies in the spleen (hence s), each colony representing the progeny of a pluripotent stem cell. Operationally, therefore, the number of colony-forming units is a measure of the number of stem cells. Acronym: CFU (09 Oct 1997) |
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| colony-forming units assay | A cytologic technique for measuring the functional capacity of stem cells by assaying their activity. (12 Dec 1998) |
| colony hybridisation | <molecular biology> A genetics lab technique used to identify which colonies of bacteria on an agar plate contain a particular sequence of DNA or a particular gene. The technique involves pressing a nylon or nitrocellulose membrane onto the plate so that each colony contributes a small smudge of itself to the membrane, then treating the membrane with chemicals and heat, then washing the membrane with a labelled probe to find the specific DNA sequence. The smudges which are indicated by the probe are then compared back to the colonies on the agar plate. This technique is often used in conjunction with experiments involving the making of genomic libraries. (09 Oct 1997) |
| mother colony | A colony which gives rise to a secondary colony (a daughter colony), the latter growing on the surface of the former; the mother colony is larger than the daughter colony, and the characteristics of the colony's may differ. (05 Mar 2000) |
| mucoid colony | A colony showing viscous or sticky growth typical of an organism producing large quantities of a carbohydrate capsule. (05 Mar 2000) |
| H colony | <cell culture> A colony of motile organisms forming a thin film of growth. Compare: O colony. Origin: Ger. Hauch, breath (05 Mar 2000) |
| smooth colony | A bacterial colony with a glistening, rounded surface; this type of colony is usually associated with increased virulence with respect to that of rough colony's. (05 Mar 2000) |
| spheroid colony | A colony of protozoa in which the individual cells are held together in a coherent spherical mass by a gelatinoid material. (05 Mar 2000) |
| daughter colony | A secondary colony growing on the surface of an older colony; it is smaller and may have characteristics different from those of the mother colony. (05 Mar 2000) |
| O colony | Growth of a nonmotile bacterium in discrete, compact colony's in contrast to a film of growth produced by some motile bacteria. Compare: H colony. Origin: Ger. Ohne Hauch, without breath (05 Mar 2000) |
| filamentous colony | In bacteriology, a colony composed of long, interwoven, irregularly disposed threads. (05 Mar 2000) |
| lenticular colony | A bacterial colony shaped like a lentil or a double-convex lens. (05 Mar 2000) |
| adrenal androgen-stimulating hormone | A putative pituitary hormone that may be responsible for increased secretion of adrenal androgens at the time of puberty. (05 Mar 2000) |
| melanocyte-stimulating hormone | <endocrinology> A releasing hormone produced in the mammalian hypophysis and related structures in lower vertebrates. Made up of _ MSH (1665D), the same as amino acids 1-13 of ACTH and _ MSH (18 amino acids, 22 in humans). Causes darkening of the skin by expansion of the melanophores but its role in mammals is unclear. Synonym: melanotropin. Acronym: MSH (22 Sep 2002) |
| hormone, thyroid stimulating | A hormone produced by the pituitary gland (at the base of the brain) that promotes the growth of the thyroid gland (in the neck) and stimulates it to produce its thyroid hormones. Normally, the rate of thyroid hormone production is controlled by the pituitary. When there are insufficient thyroid hormones in the body for normal functioning of the cells, the pituitary releases tsh. Tsh in turn stimulates the thyroid gland to produce more thyroid hormones. In contrast, when there is excessive amount of thyroid hormones, the pituitary gland stops producing tsh. The tsh level then falls and thyroid hormone production is reduced. This mechanism maintains a relatively constant level of thyroid hormones circulating in the blood. This phenomenon is analogous to a thermostat used for temperature regulation in a room: when the temperature rises, the thermostat shuts the heater off and the room temperature falls back to normal. High levels of thyroid hormones cause the tsh level to fall, resulting in no further stimulation of the thyroid gland. In hyperthyroidism, there are continuously elevated levels of the thyroid hormones. Tsh is also known as thyrotropin. (12 Dec 1998) |