| growth cone | <cell biology> A specialised region at the tip of a growing neurite that is responsible for sensing the local environment and moving toward the neuron's target cell. Growth cones are hand shaped, with several long filopodia that differentially adhere to surfaces in the embryo. Growth cones can be sensitive to several guidance cues, for example: surface adhesiveness, growth factors, neurotransmitters and electric fields (galvanotropism). (18 Nov 1997) |
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| growth cone collapse | <cell biology> Loss of motile activity and cessation of advance by growth cones. There are now thought to be specific molecules that inhibit the motility of particular growth cones and are important in establishing correct pathways in developing nervous systems. See: axon pathfinding. (18 Nov 1997) |
| growth control | <cell biology> When applied to cells usually means control of growth of the population, i.e. Of the rate of division rather than of the size of an individual cell. (18 Nov 1997) |
| growth curve | A graphic representation of the change in size of an individual or a population over a period of time. (05 Mar 2000) |
| growth disorders | Deviations from the average values for a specific age and sex in any or all of the following: height, weight, skeletal proportions, osseous development, or maturation of features. The concept includes both acceleration and retardation of growth. (12 Dec 1998) |
| growth factor | <biochemistry> A complex family of polypeptide hormones or biological factors that are produced by the body to control growth, division and maturation of blood cells by the bone marrow. They regulate the division and proliferation of cells and influence the growth rate of some cancers. These factors occur naturally but some can be synthesised using molecular biology techniques and are used clinically to stimulate normal white cell production following chemotherapy or bone marrow transplantation. Examples include epidermal growth factor, platelet-derived growth factor, fibroblast growth factor. Insulin and somatomedin are also growth factors, the status of nerve growth factor is more uncertain. Perturbation of growth factor production or of the response to growth factor is important in neoplastic transformation. (29 Sep 1997) |
| growth factors | Proteins involved in cell differentiation and growth.Growth factors are essential to the normal cell cycle, and are thus vital elements in the life of animals from conception to death. Among other things, they mediate foetal development, play a role in maintenance and repair of tissues, stimulate production of blood cells, and, gone awry, participate in cancerous processes. (05 Mar 2000) |
| growth hormone | <endocrinology, hormone> Polypeptide (191 amino acids) produced by anterior pituitary that stimulates liver to produce somatomedins 1 & 2. (13 Nov 1997) |
| growth hormone inhibiting hormone | <protein> Gastrointestinal and hypothalmic peptide hormone (two forms: 14 and 28 residues), found in gastric mucosa, pancreatic islets, nerves of the gastrointestinal tract, in posterior pituitary and in the central nervous system. Inhibits gastric secretion and motility: in hypothalamus/pituitary inhibits somatotropin release. (18 Nov 1997) |
| growth hormone-producing adenoma | <tumour> An adenoma that produces the clinical picture of gigantism or acromegaly, although a third of the cells have no granules or are a mixture of acidophils and chromophobes; some tumours may secrete both growth hormone and prolactin; often an acidophil or eosinophil adenoma. (05 Mar 2000) |
| growth hormone-regulating hormone | <endocrinology> Hypothalamic hormones that induce (somatoliberin) or inhibit (somatostatin) the release of growth hormone (somatotropin). (18 Nov 1997) |
| growth hormone-releasing factor | <endocrinology> Peptide hormone related to the glucagon family, released from the pituitary, acts on the adenohypophysis to release growth hormone. Synonym: somatoliberin, growth hormone-releasing factor. (20 Sep 2002) |
| growth hormone-releasing hormone | <endocrinology> Peptide hormone related to the glucagon family, released from the pituitary, acts on the adenohypophysis to release growth hormone. Synonym: somatoliberin, growth hormone-releasing factor. (20 Sep 2002) |
| growth hormone stimulation test | <investigation> A test which measures the level of human growth hormone in response to the administration of the amino acid arginine. This test measures the ability of the pituitary gland to secrete growth hormone. Normal values in children are: 48 ng/ml. Normal values in men are 10 ng/ml. Normal values in women are 15 ng/ml. This test is used to evaluate infants with growth retardation. It may also be part of an evaluation for a pituitary tumour. Failure of arginine to raise growth hormone levels may indicate hypopituitarism or dwarfism. (27 Sep 1997) |
| growth hormone suppression test | <investigation> A test to determine if growth hormone is suppressed by hyperglycaemia. Growth hormone blood levels are determined sequentially after ingestion of a glucose-rich meal. If growth hormone levels remain elevated (after the glucose is given) then acromegaly or gigantism is suspected. (27 Sep 1997) |