| elementary bodies | Old term for virions, especially the largest virus particles, visible by light microscopy when stained. Synonym: platelet. (05 Mar 2000) |
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| elementary granule | A particle of blood dust, or haemoconia. (05 Mar 2000) |
| elementary particle interactions | The interactions of particles responsible for their scattering and transformations (decays and reactions). Because of interactions, an isolated particle may decay into other particles. Two particles passing near each other may transform, perhaps into the same particles but with changed momenta (elastic scattering) or into other particles (inelastic scattering). Interactions fall into three groups: strong, electromagnetic, and weak. (12 Dec 1998) |
| elementary particles | <radiobiology> at a nuclear-energy level: electron & positron - seem to be stable, proton - thought to be stable, life greater than 10^30 sec, neutron - decays in ?6 min unless its in a nucleus, which often extends its life. Other particles important for nuclear energy: Muon, neutrino (m, e, tau), photon, Muonic atoms, Pi-meson antiparticles (09 Oct 1997) |
| elementary step | <chemistry> Reaction mechanisms are broken down into elementary steps. For each step the the reactants are directly involved in forming the transition state. Therefore a rate law can be written from an elementary step but not from an overall reaction. (09 Jan 1998) |
| Zimmermann's elementary particle | <haematology> A discoid cell (3m diameter) found in large numbers in blood, important for blood coagulation and for haemostasis by repairing breaches (small breaks) in the walls of blood vessels. Platelet _ granules contain lysosomal enzymes, dense granules contain ADP (a potent platelet aggregating factor) and serotonin (a vasoactive amine). They also release platelet-derived growth factor which presumably contributes to later repair processes by stimulating fibroblast proliferation. Synonym: thrombocytes. (09 Oct 1997) |
| acetone body | <biochemistry> Any of the three compounds created by acetyl coenzyme A (acetoacetate, hydroxybutyrate, and acetone) which are water-soluble cellular fuels normally exported by the liver. They can build up in the blood and body tissues because of starvation, untreated diabetes mellitus, or other disorders that interfere with carbohydrate metabolism. The body rids itself of ketones mainly through urine, but it rids itself of acetone through the lungs, which gives the breath a characteristic fruity odour. If ketones build up in the body long enough, they cause serious illness and coma (see ketoacidosis.) (09 Oct 1997) |
| acute inclusion body encephalitis | The most common acute encephalitis, caused by HSV-1; affects persons of any age; preferentially involves the inferomedial portions of the temporal lobe and the orbital portions of the frontal lobes; pathologically, severe haemorrhagic necrosis is present along with, in the acute stages, intranuclear eosinophilic inclusion bodies in the neurons and glial cells. Synonym: acute inclusion body encephalitis, herpes encephalitis. (05 Mar 2000) |
| adrenal body | See adrenal gland. (12 Dec 1998) |
| alveolar body | That portion of bone in either the maxilla or the mandible which surrounds and supports the teeth. (12 Dec 1998) |
| amygdaloid body | Almond-shaped group of basal nuclei anterior to the inferior horn of the lateral ventricle of the brain, within the temporal lobe. The amygdala is part of the limbic system. (12 Dec 1998) |
| amylogenic body | A plant plastid involved in the synthesis and storage of starch. Found in many cell types, but particularly storage tissues. Characteristically has starch grains in the plastid stroma. (18 Nov 1997) |
| anococcygeal body | <anatomy> A musculofibrous band that passes between the anus and the coccyx. Synonym: ligamentum anococcygeum, anococcygeal body, raphe anococcygea, Symington's anococcygeal body. (05 Mar 2000) |
| anterior quadrigeminal body | The paired, larger, rounded anterior eminence of the laminae of mesencephalic tectum; major afferent connections of the superficial layers are the retina and striate cortex; input to deep layers of the colliculus are polymodal. Its efferent connections are with the lower brainstem and spinal cord (tectobulbar tract and tectospinal tract) and with the pulvinar and other cell groups in the caudal part of the thalamus; participates in extrageniculate visual pathway. Synonym: colliculus superior, anterior quadrigeminal body, corpus quadrigeminum anterius. (05 Mar 2000) |
| aortic body tumour | Aortic body, carotid body, chemoreceptor, or glomus jugulare tumour; nonchromaffin paraganglioma; receptoma; a relatively rare, usually benign neoplasm originating in the chemoreceptor tissue of the carotid body, glomus jugulare, and aortic bodies; consisting histologically of rounded or ovoid hyperchromatic cells that tend to be grouped in an alveolus-like pattern within a scant to moderate amount of fibrous stroma and a few large thin-walled vascular channels. Compare: paraganglioma. Synonym: aortic body tumour, carotid body tumour, chemoreceptor tumour, glomus jugulare tumour, nonchromaffin paraganglioma. Origin: chemo-+ G. Dektes, receiver, fr. Dechomai, to receive, + -oma, tumour (05 Mar 2000) |