| primary biliary cirrhosis | <gastroenterology> A rare form of liver disease which results in the irreversible destruction of the liver and bile ducts. The cause is unknown, but is thought to be an autoimmune mechanism. (06 Mar 1998) |
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| primary brain tumour | <neurology, oncology> May be subdivided into primary brain tumours and the more common, secondary brain tumours. Primary brain tumours (for example astrocytoma, craniopharyngioma, glioma, ependymoma, neuroglioma, oligodendroglioma, glioblastoma multiforme, meningioma, medulloblastoma) arise from the uncontrolled proliferation of cells within the brain. Secondary brain tumours occur from the spread of cancer into the brain from a distant cancerous organ (metastasis). Common symptoms of a brain tumour include headache, nausea, vomiting, seizures, change in mentation, neurologic symptoms and loss of memory. (06 Mar 1998) |
| primary brain vesicle | Each of the three divisions of the early embryonic brain (prosencephalon, mesencephalon, and rhombencephalon). Synonym: encephalic vesicle, primary brain vesicle. (05 Mar 2000) |
| primary bronchus | The main bronchus arising at the tracheal bifurcation and extending into the developing lung of the embryo. (05 Mar 2000) |
| primary butyl alcohol | Propylcarbinol, CH3CH2CH2CH2OH, the butyl alcohol of fermentation; isobutyl alcohol, isopropylcarbinol, 2-methyl-1-propanol, (CH3)2CHCH2OH; narcotic in high concentrations, secondary butyl alcohol, ethylmethylcarbinol, 2-butanol, CH3CH2CH(CH3)OH; and (05 Mar 2000) |
| primary carcinoma | <tumour> Carcinoma at the site of origin, with local invasion in that organ. (05 Mar 2000) |
| primary cardiomyopathy | Cardiomyopathy of unknown or obscure cause. A disease that affects mainly the heart muscle, sparing other cardiac structures and usually resulting in fibrosis, hypertrophy, or both. Synonym: idiopathic cardiomyopathy. (05 Mar 2000) |
| primary care | The medical home for a patient, ideally providing continuity and integration of health care. All family physicians and most paediatricians and internists are in primary care. The aims of primary care are to provide the patient with a broad spectrum of care, both preventive and curative, over a period of time and to coordinate all of the care the patient receives. (12 Dec 1998) |
| primary caries | Initial lesions produced by direct extension from an external surface. (05 Mar 2000) |
| primary cell | <cell biology> A cell or cell line taken directly from a living organism, which is not immortalised. (06 Mar 1998) |
| primary cell culture | <cell culture> Of animal cells, the cells taken from a tissue source and their progeny grown in culture before subdivision and transfer to a sub culture. (18 Nov 1997) |
| primary cell wall | <plant biology> A plant cell wall that is still able to expand, permitting cell growth. Growth is normally prevented when a secondary wall has formed. Primary cell walls contain more pectin than secondary walls and no lignin is present until a secondary wall has formed on top of them. (06 Mar 1998) |
| primary cementum | Cementum that has no cementocytes; may cover the entire root of the tooth, but often is missing on the apical third of the root. (05 Mar 2000) |
| primary centre of ossification | This is the first site where bone begins to form in the shaft of a long bone or in the body of an irregular bone. Synonym: punctum ossificationis primarium, primary point of ossification. (05 Mar 2000) |
| primary choana | Primitive choana, initial opening of the nasal pits and olfactory sac of the embryo into the rostral part of the primordial oronasal cavity, before the formation of the secondary palate. (05 Mar 2000) |