| nerve 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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| nerve growth factor | <growth factor> A peptide (13.26 kD) of 118 amino acids (usually dimeric) with both chemotropic and chemotrophic properties for sympathetic and sensory neurons. Found in a variety of peripheral tissues, nerve growth factor attracts neurites to the tissues by chemotropism, where they form synapses. The successful neurons are then protected from neuronal death by continuing supplies of nerve growth factor. It is also found at exceptionally high levels in snake venom and male mouse submaxillary salivary glands, from which it is commercially extracted. Nerve growth factor was the first of a family of nerve tropic factors to be discovered. Amino acids 1-81 show homology with proinsulin. Besides its peripheral actions, nerve growth factor selectively enhances the growth of cholinergic neurons that project to the forebrain and that degenerate in Alzheimer's disease. Acronym: NGF (18 Nov 1997) |
| nerve growth factor antiserum | An antiserum containing antibodies against nerve growth factor; when injected into newborn animals the majority of sympathetic ganglion cells are permanently destroyed, resulting in hypoinnervation of peripheral tissues. Synonym: NGF antiserum. (05 Mar 2000) |
| nerve growth factors | Factors which enhance the growth potentialities of sensory and sympathetic nerve cells. (12 Dec 1998) |
| new growth | <oncology, pathology> New and abnormal growth of tissue, which may be benign or cancerous. (16 Dec 1997) |
| density dependent inhibition of growth | <cell culture> The phenomenon exhibited by most normal (anchorage dependent) animal cells in culture that stop dividing once a critical cell density is reached. The critical density is considerably higher for most cells than the density at which a monolayer is formed, for this reason, most cell behaviourists prefer the term density dependent inhibition of growth as this avoids any confusion with contact inhibition of locomotion, a totally different phenomenon that is contact dependent. (12 Jan 1998) |
| differential growth | Different rates of growth in associated tissues or structures; used especially in embryology when the differences in growth rates result in changing the original proportions or relations. (05 Mar 2000) |
| insulin like growth factor | <growth factor> Insulin like growth factors I and II are polypeptides with considerable sequence similarity to insulin. They are capable of eliciting the same biological responses, including mitogenesis in cell culture. On the cell surface, there are two types of insulin like growth factor receptor, one of which closely resembles the insulin receptor (which is also present). Insulin like growth factor I = somatomedin A = somatomedin C Insulin like growth factor II = MSA (Multiplication stimulating activity). Insulin like growth factor 1 is released from the liver in response to growth hormone. Acronym: IGF (18 Nov 1997) |
| insulin-like growth-factor binding protein 1 | One of the six homologous proteins that specifically bind insulin-like growth factors (somatomedins) and modulate their mitogenic and metabolic actions. The function of this protein is not completely defined. However, several studies demonstrate that it inhibits igf binding to cell surface receptors and thereby inhibits igf-mediated mitogenic and cell metabolic actions. (proc soc exp biol med 1993;204(1):4-29) (12 Dec 1998) |
| insulin-like growth factor-binding protein 2 | One of the six homologous soluble proteins that bind insulin-like growth factors (somatomedins) and modulate their mitogenic and metabolic actions at the cellular level. (12 Dec 1998) |
| insulin-like growth factor binding protein 3 | One of the six homologous soluble proteins that bind insulin-like growth factors (somatomedins) and modulate their mitogenic and metabolic actions at the cellular level. (12 Dec 1998) |
| insulin like growth-factor-binding protein 4 | One of the six homologous soluble proteins that bind insulin-like growth factors (somatomedins) and modulate their mitogenic and metabolic actions at the cellular level. (12 Dec 1998) |
| insulin-like growth-factor-binding-protein 5 | One of the six homologous soluble proteins that bind insulin-like growth factors (somatomedins) and modulate their mitogenic and metabolic actions at the cellular level. (12 Dec 1998) |
| insulin-like-growth-factor-binding protein 6 | One of the six homologous soluble proteins that bind insulin-like growth factors (somatomedins) and modulate their mitogenic and metabolic actions at the cellular level. (12 Dec 1998) |
| insulin-like growth-factor-binding proteins | A family of soluble proteins that bind insulin-like growth factors and modulate their biological actions at the cellular level. (int j gynaecol obstet 1992;39(1):3-9) (12 Dec 1998) |