| basal bone | The osseus tissue of the mandible and maxillae except the alveolar processes. (05 Mar 2000) |
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| basal cell | <pathology> General term for relatively undifferentiated cells in an epithelial sheet that give rise to more specialised cells act as stem cells). In the stratified squamous epithelium of mammalian skin the basal cells of the epidermis (stratum basale) give rise by an unequal division to another basal cell and to cells that progress through the spinous, granular and horny layers, becoming progressively more keratinised, the outermost being shed as squames. In olfactory mucosa the basal cells give rise to olfactory and sustentacular cells. In the epithelium of epididymis their function is unclear, but they probably serve as stem cells. (13 Nov 1997) |
| basal cell adenoma | <tumour> A benign tumour of major or minor salivary glands or other organs composed of small cells showing peripheral palisading. (05 Mar 2000) |
| basal cell carcinoma | <oncology, tumour> The most common form of skin cancer. A malignant growth of epidermal tissue, specifically basal cells. most common in the fair-skinned on sun-exposed areas (especially the face). (15 Nov 1997) |
| basal cell epithelioma | <oncology, tumour> The most common form of skin cancer. A malignant growth of epidermal tissue, specifically basal cells. most common in the fair-skinned on sun-exposed areas (especially the face). (15 Nov 1997) |
| basal cell hyperplasia | Increase in the number of cells in an epithelium resembling the basal cells. (05 Mar 2000) |
| basal cell layer | The deepest layer of the epidermis, composed of dividing stem cells and anchoring cells. Synonym: basal cell layer, columnar layer, germinative layer, palisade layer, stratum basale, stratum cylindricum, stratum germinativum. (05 Mar 2000) |
| basal cell nevus | A hereditary disease noted in infancy or adolescence, characterised by lesions of the eyelids, nose, cheeks, neck, and axillae, appearing as uneroded flesh-coloured papules, some becoming pedunculated, and histologically indistinguishable from basal cell epithelioma; also noted are punctate keratotic lesions of the palms and soles; the lesions usually remain benign, but in some cases ulceration and invasion occur and are evidence of malignant change; autosomal dominant inheritance. (05 Mar 2000) |
| basal cell nevus syndrome | <syndrome> An inherited group of defects which involve abnormalities of the skin, eyes, nervous system, endocrine, glands and bones. The condition is characterised by an unusual facial appearance and a predisposition for skin cancer. (27 Sep 1997) |
| basal cell papilloma | A benign skin lesion resulting from excessive growth of the top layer of skin cells. It usually is found in persons over 30 years old and may be few or numerous. (12 Dec 1998) |
| basal cells | Small, round cells found in the lower part, or base, of the epidermis, the outer layer of the skin. (12 Dec 1998) |
| basal cistern | A dilation of the subarachnoid space in front of the pons, where the arachnoid membrane stretches across between the two temporal lobes over the base of the diencephalon. See: interpeduncular fossa. Synonym: cisterna interpeduncularis, basal cistern, cisterna basalis, cisterna cruralis, Tarin's space. (05 Mar 2000) |
| basal corpuscle | <cell biology> Structure found at the base of eukaryotic cilia and flagella consisting of a continuation of the nine outer sets of axonemal microtubules but with the addition of a C tubule to form a triplet (like the centriole). May be self replicating and serves as a nucleating centre for axonemal assembly. Anchored in the cytoplasm by rootlets. Synonymous with kinetosome. (18 Nov 1997) |
| basal diet | A diet having a caloric value equal to the basal heat production and sufficient quanties of essential nutrients to meet basic needs, in experiments in nutrition, a diet from which a given constituent (e.g., a vitamin, mineral, or amino acid), the nutritional value of which is to be determined, is omitted for a period and the effects observed; the subject is observed for a second period during which the ingredient being studied is added to the diet. (05 Mar 2000) |
| basal ganglia | <anatomy> Three large subcortical nuclei of the vertebrate brain: the putamen, the caudate nucleus and the globus pallidus. They participate in the control of movement along with the cerebellum, the corticospinal system and other descending motor systems. Lesions of the basal ganglia occur in a variety of motor disorders including Parkinson's disease and Huntingdon's chorea. (15 Nov 1997) |