| astroependymoma | <tumour> A glial neoplasm composed of a mixed population of astrocytic and ependymal cells. (05 Mar 2000) |
|---|---|
| astroglia | 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) |
| astroglia cell | <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) |
| astrogliosis | <pathology> Hypertrophy of the astroglia, usually in response to injury. (18 Nov 1997) |
| astrography | The art of describing or delineating the stars; a description or mapping of the heavens. Origin: Astro'cf. Source: Websters Dictionary (01 Mar 1998) |
| astroid | Star-shaped. Origin: G. Astroeides, fr. Astron, star, + eidos, resemblance (05 Mar 2000) |
| astroite | A radiated stone or fossil; star-stone. Alternative forms: astrite and astrion. Origin: L. Astroites: cf. F. Astroite. Source: Websters Dictionary (01 Mar 1998) |
| astrokinetic | Relating to movement of the centrosome and astrosphere of a dividing cell. Origin: G. Astron, star, + kinesis, movement (05 Mar 2000) |
| astrolabe | 1. <astronomy> An instrument for observing or showing the positions of the stars. It is now disused. Among the ancients, it was essentially the armillary sphere. A graduated circle with sights, for taking altitudes at sea, was called an astrolabe in the 18th century. It is now superseded by the quadrant and sextant. 2. A stereographic projection of the sphere on the plane of a great circle, as the equator, or a meridian; a planisphere. Origin: OE. Astrolabie, astrilabe, OF. Astrelabe, F. Astrolabe, LL. Astrolabium, fr. Gr.; star +, to take. Source: Websters Dictionary (01 Mar 1998) |
| astrolithology | <study> The science of aerolites. (04 Mar 1998) |
| astrologer | 1. One who studies the stars; an astronomer. 2. One who practices astrology; one who professes to foretell events by the aspects and situation of the stars. See: Astrology. Source: Websters Dictionary (01 Mar 1998) |
| astrological | Of or pertaining to astrology; professing or practicing astrology. "Astrologi learning." . "Astrological prognostication." . Astrolog"ically. Origin: Gr. Source: Websters Dictionary (01 Mar 1998) |
| astrologize | To apply astrology to; to study or practice astrology. Source: Websters Dictionary (01 Mar 1998) |
| astrology | <study> In its etymological signification, the science of the stars; among the ancients, synonymous with astronomy; subsequently, the art of judging of the influences of the stars upon human affairs, and of foretelling events by their position and aspects. Astrology was much in vogue during the Middle Ages, and became the parent of modern astronomy, as alchemy did of chemistry. It was divided into two kinds: judicial astrology, which assumed to foretell the fate and acts of nations and individuals, and natural astrology, which undertook to predict events of inanimate nature, such as changes of the weather, etc. Origin: F. Astrologie, L. Astrologia, fr. Gr, fr. Astronomer, astrologer; star + discourse, to speak. See Star. (04 Mar 1998) |
| astromantic | Of or pertaining to divination by means of the stars; astrologic. Origin: Gr. Astrology. Source: Websters Dictionary (01 Mar 1998) |