| companion cell | <plant biology> Relatively small plant cell, with little or no vacuole, found adjacent to a phloem sieve tube and originating with the latter from a common mother cell. Thought to be involved in translocation of sugars in and out of the sieve tube. (05 Jan 1998) |
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| companion lymph nodes of accessory nerve | The nodes of the lateral deep cervical group that are located along the accessory nerve; their efferent vessels pass to the supraclavicular lymph nodes. Synonym: companion lymph nodes of accessory nerve, nodi lymphatici comitantes nervi accessorii. (05 Mar 2000) |
| companion vein | A vein accompanying another structure. Synonym: accompanying vein, companion vein. (05 Mar 2000) |
| comparascope | <instrument> A microscope accessory by means of which an observer may directly compare simultaneously the findings in two microscopic preparations. Origin: L. Comparo, to compare, + G. Skopeo, to view (05 Mar 2000) |
| comparative anatomy | The comparative study of animal structure with regard to homologous organs or parts. (05 Mar 2000) |
| comparative medicine | A field of study concentrating on similarities and differences between veterinary medicine and human medicine. (05 Mar 2000) |
| comparative pathology | The pathology of diseases of animals, especially in relation to human pathology. (05 Mar 2000) |
| comparative physiology | The science concerned with the differences in the vital processes in different species of organisms, particularly with a view to the adaptation of the processes to the specific needs of the species, to illuminating the evolutionary relationships among different species, or to establishing other interspecific generalizations and relationships. (05 Mar 2000) |
| comparative psychology | A branch of psychology concerned with the study and comparison of the behaviour of organisms at different levels of phylogenic development to discover developmental trends. (05 Mar 2000) |
| comparator microscope | <instrument> A device constructed with one or more microscope's having micrometer eyepieces used to measure dimensional changes during setting or temperature changes. (05 Mar 2000) |
| compartment | <biology> In the insect wing, for example: there are two compartments, anterior and posterior, each containing several clones, but clones do not cross the boundary. It seems from studies with homoeotic mutants that cells in different compartments are expressing different sets of genes. The evidence for such developmental compartments in vertebrates is sparse at present. (18 Nov 1997) |
| compartment syndrome | <syndrome> A group of symptoms which indicate a nerve, blood vessel or tendon is being constricted due to swelling within a closed anatomic space. A compartment syndrome may occur in an extremity after trauma (fracture) or inflammation (carpal tunnel syndrome). Some medications can also precipitate this condition. Symptoms include numbness, tingling, pain or loss of movement in an extremity. Surgery may be indicated if symptoms are severe or prolonged. (05 Jan 1998) |
| compartment syndromes | Conditions in which increased pressure within a limited space compromises the circulation and function of tissue within that space. Compartmentation involves mainly the leg but also involved are the forearm, arm, thigh, shoulder, and buttock. Some of the causes of increased pressure are trauma, tight dressings, haemorrhage, and exercise. Sequelae include nerve compression, paralysis, and contracture. (12 Dec 1998) |
| compartmental model | <epidemiology> A mathematical model which divides hosts into different compartments according to their infectious state. A typical model for microparasites might be an SEIR model. Sometimes referred to as a prevalence model. (05 Dec 1998) |
| compartmental syndrome | <syndrome> A condition in which increased pressure in a confined anatomical space adversely affects the circulation and threatens the function and viability of the tissues therein. (05 Mar 2000) |