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astigmatometer, astigmometer

(as″tig-mă-tom′ĕt-ĕr, -mom′ĕt-ĕr) [astigmatism + -meter] An instrument for measuring astigmatism.


(ă-stig′mē-ă) Astigmatism.


A suffix used in pharmacology for an antihistamine that blocks H1 histamine receptors.

astomatous, astomous

(ā″tōm′ă-tŭs, ă-stō′mŭs) [1an- + stoma] In certain protozoa, without a mouth or oral aperture.


(ă-stōm′ē-ă) [1an- + stoma + -ia] Congenital absence of the mouth.

Astragalus membranaceus

(mem″bră-nā′s(h)ē-ŭs) A flowering perennial plant of the legume family, from whose roots a brew is concocted that is used in traditional Chinese medicine as an herbal remedy as immune stimulant and as a treatment for colds and flu.


(ă-strik′shŏn) [L. astrictio, tightening] Action of an astringent.


(ă-strin′jĕnt) [L. astringere, to bind fast] 1. Drawing together, constricting, binding. 2. An agent that has a constricting or binding effect, i.e., one that checks bleeding or secretion of body fluids by coagulation of proteins on a cell surface. The principal astringents are salts of metals such as lead, iron, zinc (ferric chloride, zinc oxide), permanganates, and tannic acid. SEE: styptic.


[Gr. astron, star] Prefix meaning star, or star-shaped.


(as′trŏ-blast″) [astro- + -blast] A cell that develops from a primitive radial glial cell and gives rise to an astrocyte. astroblastic (as″trŏ-blas′tik), adj.


(as″trŏ-blas-tō′mă) [astro- + blastoma] A grade II astrocytoma, composed of cells with abundant cytoplasm and two or three nuclei.


(as′trŏ-sīt″) [astro- + -cyte] A common asterisk-shaped glial cell with many radiating cell processes. Astrocytes are neuroectodermal cells that begin as radial glia that later mature into multipolar cells. Astrocytes are spread homogeneously throughout the central nervous system and each astocyte occupies its own compartment of neuropil. The cell processes of an astrocyte are covered with leaflets of cytoplasm that contact axons, synaptic structures, blood vessels, and neighboring glia. Touching astrocytes are electrically coupled and can propagate calcium potentials and within its microdomain of neuropil, each astrocyte regulates the extracellular concentration of certain molecules, including neurotransmitters. In areas of injury, astrocytes can proliferate. SYN: astroglial cell; macroglia; spider cell. SEE: glial cell; illus. astrocytic (as″trŏ-sit′ik), adj.






(as″trō-sī-tō′mă) [astro- + cyt- + -oma] Tumor of the brain or spinal cord composed of astrocytes. Tumors are graded according to how ...

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