| astral fibres | Fibre's (fibrils) radiating from the centrosphere toward the periphery of the cell as seen with a light microscope; revealed as microtubules under the electron microscope. Compare: kinetochore fibres, polar fibres. (05 Mar 2000) |
|---|---|
| astrapophobia | <psychology> Morbid fear of lightning. Origin: G. Astrape, lightning, + phobos, fear (05 Mar 2000) |
| astriction | 1. The act of binding; restriction; also, obligation. 2. <medicine> A contraction of parts by applications; the action of an astringent substance on the animal economy. Constipation. 3. Astringency. 4. An obligation to have the grain growing on certain lands ground at a certain mill, the owner paying a toll. The lands were said to be astricted to the mill. Origin: L. Astrictio. Source: Websters Dictionary (01 Mar 1998) |
| astringency | The quality of being astringent; the power of contracting the parts of the body; that quality in medicines or other substances which causes contraction of the organic textures; as, the astringency of tannin. Source: Websters Dictionary (01 Mar 1998) |
| astringent | <pharmacology> Causing contraction, usually locally after topical application. Origin: L. Astringens (18 Nov 1997) |
| astringents | Agents that cause contraction, usually locally after topical application. (12 Dec 1998) |
| astrobiology | <study> The study of life that potentially exists on planets or celestial bodiesother thanEarth. (09 Oct 1997) |
| astroblast | An embryonic astrocyte. (18 Nov 1997) |
| astroblastoma | <oncology, tumour> A rare form of cancer characterised by tumours made up of large cells withtwo or three nuclei. (09 Oct 1997) |
| astrocele | Synonym: centrosphere. Origin: G. Astron, star, + koilia, hollow (05 Mar 2000) |
| astrocyte | <pathology> A glial cell found in vertebrate brain, named for its characteristic star like shape. Astrocytes lend both mechanical and metabolic support for neurons, regulating the environment in which they function. See: oligodendrocytes. (18 Nov 1997) |
| astrocytes | The largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from "star" cells) are irregularly shaped with many long processes, including those with "end feet" which form the glial (limiting) membrane and directly and indirectly contribute to the blood-brain barrier. They regulate the extracellular ionic and chemical environment, and "reactive astrocytes" (along with microglia) respond to injury. Astrocytes have high- affinity transmitter uptake systems, voltage-dependent and transmitter-gated ion channels, and can release transmitter, but their role in signaling (as in many other functions) is not well understood. (12 Dec 1998) |
| astrocytoma | <oncology, tumour> A neuro ectodermal tumour (glioma) arising from astrocytes. Probably the commonest glioma, it has a tendency to become anaplastic. (18 Nov 1997) |
| astrocytosis | <pathology> An abnormal increase in the number of astrocytes due to the destruction of nearby neurons, typically because of hypoglycaemia or oxygen deprivation. (09 Oct 1997) |
| astrocytosis cerebri | A diffuse intracranial neoplasm of astrocytic origin. Synonym: astrocytosis cerebri, glioblastosis cerebri. (05 Mar 2000) |