| 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 inhibitors | Endogenous or exogenous substances which inhibit the normal growth of human and animal cells or micro-organisms, as distinguished from those affecting plant growth (= plant growth regulators). (12 Dec 1998) |
| growth medium | <cell culture> A synthetic medium which is filled with nutrients necessary to the growth of microorganisms or cells being cultured in the lab. (09 Oct 1997) |
| growth milestones | <paediatrics> (1-3 years) In ascending order: masters walking, recognises gender differences, uses up to 8 words and understands simple commands, able to run, pivot and walk backwards, uses spoon to feed self, can name pictures of common objects, can point to body parts, imitates speech of others, begins pedaling tricycle, learns to take turns in play with other children, able to feed self neatly with minimal spill, able to say first and last name, able to draw a line when shown, dresses self with minimal help, learns to share toys without parent direction (12-18 years) In ascending order: boys exhibit secondary sexual characteristics (chest, facial, axillary and pubic hair growth voice changes, penile enlargement), movement into adult height/weight category, cognitive abilities move from simply concrete to abstract, peer acceptance and recognition is vital (3-6 years) In ascending order: rides tricycle well, able to draw a circle, able to draw stick figures, hops on one foot, catches a bounced ball, understands size concepts, enjoys rhymes and word play, able to skip, increased independence in performing tasks without parental assistance, begins to ride bicycle, understands time concepts, begins to recognise written words, starts reading skills, starts school (6-12 years) In ascending order: understands and is able to follow sequential directions, beginning skills for team sports, begins to lose baby teeth and erupt permanent teeth, reading skills develop further, peer recognition becomes important, girls begin to demonstrate secondary sexual characteristics (pubic hair, axillary hair, breast development), first menstrual period may occur (birth-1 year) In ascending order: displays social smile, rolls over by self, able to sit alone without support, babbling, plays peek-a-boo, eruption of first tooth, pulls self to standing position, walks while holding on to furniture or other support, says mama or dada in proper situations, able to drink from cup, understands NO and will stop activity in response, walks without support (27 Sep 1997) |
| growth-onset diabetes | A chronic condition in which the pancreas makes little or no insulin because the beta cells have been destroyed. The body is then not able to use the glucose (blood sugar) for energy. IDDM usually comes on abruptly, although the damage to the beta cells may begin much earlier. The signs of IDDM are a great thirst, hunger, a need to urinate often, and loss of weight. To treat the disease, the person must inject insulin, follow a diet plan, exercise daily, and test blood glucose several times a day. IDDM usually occurs in children and adults who are under age 30. This type of diabetes used to be known as juvenile diabetes, juvenile-onset diabetes, and ketosis-prone diabetes. (09 Oct 1997) |
| growth phase | <microbiology> The characteristic periods in the growth of a bacterial culture, as indicated by the shape of a graph of viable cell number versus time. (09 Oct 1997) |
| growth plate | <physiology> The area between the epiphysis and the diaphysis within which bone growth occurs. (12 Dec 1998) |
| growth quotient | <biology> The fractional part or percentage of the entire food energy which is utilised for growth in the young animal. (05 Mar 2000) |
| growth rate | <biology, cell culture, ecology> The rate, or speed, at which the number of organisms in a population increases. This can be calculated by dividing the change in the number of organisms from one point in time to another by the amount of time in the interval between the points of time. The phrase is most often used to describe growth of cells or microorganisms in laboratory cultures and usually expressed as the generation time. (21 Jun 2000) |