| gastrea theory | That the two-layered gastrula is the ancestral form of all multicellular animals. Synonym: gastrea theory. (05 Mar 2000) |
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| gate-control theory | A theory to explain the mechanism of pain; small fibre afferent stimuli, particularly pain, entering the substantia gelatinosa can be modulated by large fibre afferent stimuli and descending spinal pathways so that their transmission to ascending spinal pathways is blocked (gated). Synonym: gate-control hypothesis. (05 Mar 2000) |
| recapitulation theory | The theory formulated by E.H. Haeckel that individuals in their embryonic development pass through stages similar in general structural plan to the stages their species passed through in its evolution; more technically phrased, the theory that ontogeny is an abbreviated recapitulation of phylogeny. Synonym: biogenetic law, law of biogenesis, Haeckel's law, law of recapitulation. (05 Mar 2000) |
| germ layer theory | The developmental biology theory that during early development, the animal embryo divides itself into two or three germ layers, each of which then proceed to further differentiate into organs and tissues specific to that particular layer. (09 Oct 1997) |
| germ theory | The theory, now a doctrine, that infectious diseases are due to the presence and functional activity of microorganisms within the body. (05 Mar 2000) |
| mass action theory | That large areas of brain tissue function as a whole in learned or intelligent action. (05 Mar 2000) |
| gestalt theory | A system which emphasizes that experience and behaviour contain basic patterns and relationships which cannot be reduced to simpler components; that is, the whole is greater than the sum of its parts. (12 Dec 1998) |
| Reed-Frost theory of epidemics | A mathematical theory to explain how epidemics originate and continue. (05 Mar 2000) |
| reed instrument theory | A no longer tenable theory stating that in human voice production the larynx functions in a manner similar to a reed musical instrument. (05 Mar 2000) |
| reentry theory | That extrasystoles are due to reentry of an impulse initiated by the sinus impulse, to which the extrasystole is coupled, into the ectopic focus. (05 Mar 2000) |
| catastrophe theory | A branch of mathematics dealing with large changes in the total system that may result from a small change in a critical variable in the system; an example is the change in the physical properties of H2O as the temperature reaches zero or 100 |
| Pauling's theory | A theory of narcosis pertaining to nonhydrogen-bonding agents; postulates the interaction of the molecules of the anaesthetic drug with water molecules in the brain. Synonym: Pauling's theory. (05 Mar 2000) |
| cell theory | <biology> The theory that all cells come from previously existing cells, and that cells are the most fundamental structural units of all living things. (26 Mar 1998) |
| cellular immune theory | A concept, put forth by Elie Metchnikoff, that cells, not antibodies, were responsible for the immune response of an organism. (05 Mar 2000) |
| celomic metaplasia theory of endometriosis | That endometrial tissue arises directly from the peritoneal mesothelium. (05 Mar 2000) |