| segmental bronchus | One of the divisions of the lobar bronchus that supplies a bronchopulmonary segment. In the right lung there are commonly ten: in the superior lobe, the apical (B1) segmental bronchus, bronchus segmentalis apicalis; posterior (B2) segmental bronchus, bronchus segmentalis (BII) posterior; and anterior (B3) segmental bronchus, bronchus segmentalis (BIII) anterior; in the middle lobe, lateral (B4) segmental bronchus, bronchus segmentalis (BIV) lateralis; and medial (B5) segmental bronchus, bronchus segmentalis medialis (BV); in the inferior lobe, superior (B6) segmental bronchus, bronchus segmentalis superior (BVI), medial basal (B7) segmental bronchus, bronchus segmentalis basalis medialis (BVII); anterior basal (B8) segmental bronchus, bronchus segmentalis basalis anterior (BVIII); lateral basal (B9) segmental bronchus, bronchus segmentalis basalis lateralis (BIX); and posterior basal (B10) segmental bronchus, bronchus segmentalis basalis posterior (BX). In the left lung there are commonly nine: in the superior lobe, the apicoposterior (B1+2) segmental bronchus, bronchus segmentalis apicoposterior (BI+I); anterior (B3) segmental bronchus, bronchus segmentalis anterior (BIII); superior lingular (B4) segmental bronchus, bronchus lingularis superior (BIV); and inferior lingular (B5) segmental bronchus, bronchus lingularis inferior (BV); in the inferior lobe, superior (B6) segmental bronchus, bronchus segmentalis superior (BVI); medial basal (B7) segmental bronchus, bronchus segmentalis basalis medialis (cardiacus) (BVII), anterior basal (B8) segmental bronchus, bronchus segmentalis basalis anterior (BVIII); lateral basal (B9) segmental bronchus, bronchus segmentalis basalis lateralis (BIX); and posterior basal (B10) segmental bronchus, bronchus segmentalis basalis posterior (BX). Synonym: bronchus segmentalis. (05 Mar 2000) |
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| segmental demyelinating polyneuropathy | A type of polyneuropathy in which almost solely the peripheral nerve myelin is affected; can be both familial (e.g., Charcot-Marie Tooth disease, type 1), or acquired (e.g., Guillain-Barre syndrome); on motor nerve conduction studies, manifested as conduction slowing or block. Synonym: segmental demyelinating polyneuropathy. (05 Mar 2000) |
| segmental fracture | A fracture in two parts of the same bone. Synonym: double fracture. (05 Mar 2000) |
| segmental glomerulonephritis | Glomerulonephritis affecting only part of a glomerulus or glomeruli. Synonym: local glomerulonephritis. (05 Mar 2000) |
| segmental glomerulosclerosis | <nephrology> A kidney disorder that results in fibrosis and scarring in the kidney glomerulus. The cause is unknown but some cases can result from reflux nephropathy. The clinical manifestation of this kidney disorder is nephrotic syndrome. Symptoms include weight gain, swelling, hypertension and foamy urine. High blood cholesterol and triglyceride levels are also seen with this disorder. Treatment has included the use of corticosteroids and immunosuppressives. Antihypertensive agents and diuretics may also be necessary. Over one-half will develop chronic renal failure within 10 years of diagnosis. (27 Sep 1997) |
| segmental mastectomy | <procedure, surgery> A surgical procedure in which only a portion of the breast is removed, including the cancer and the surrounding margin of healthy breast tissue. (09 Oct 1997) |
| segmental neuritis | Inflammation occurring at several points along the course of a nerve, segmental demyelinating neuropathy (05 Mar 2000) |
| segmental plate | In a young embryo, the thickened dorsal portion of the undifferentiated paraxial mesoderm which becomes metamerically divided to form the mesodermal somites. Synonym: segmental plate. (05 Mar 2000) |
| segmental sphincter | A sphincter of a segment of an organ, a tube, or a canal, and longer than an annular sphincter. (05 Mar 2000) |
| segmental tubule | An excretory tubule of the mesonephros. Synonym: segmental tubule. (05 Mar 2000) |
| segmental zone | In a young embryo, the thickened dorsal portion of the undifferentiated paraxial mesoderm which becomes metamerically divided to form the mesodermal somites. Synonym: segmental plate. (05 Mar 2000) |
| segmentation | <biology> Organisation of the body into repeating units called segments is a common feature of several phyla, for example arthropods and annelids, although the segments arise by very different mechanisms. Segmentation also occurs during embryonic development in vertebrates, for example partition of the mesoderm into somites and is a feature of early CNS development. See: rhombomeres, neuromeres. (18 Nov 1997) |
| segmentation cavity | The cavity in the blastula of a developing embryo. Synonym: blastocoele, cleavage cavity, segmentation cavity. Origin: blasto-+ G. Koilos, hollow (05 Mar 2000) |
| segmentation gene | <molecular biology> Genes required for the establishment of segmentation in the embryo. In Drosophila about 20 such genes are required. A development pattern of the embryo of the fruit fly Drosophila where the embryo looks like a stack of discs. Each disc is a segment, and each segment consists of two compartments (an anterior and posterior). Various parts of the adult fruit fly (wings, legs, eyes, etc.) arise from specific segments. (09 Oct 1997) |
| segmentation nucleus | The compound nucleus in the impregnated ovum, formed by conjugation of the nuclei of the ovum and spermatozoon (female and male pronuclei), the zygote nucleus after it commences the first cleavage division. (05 Mar 2000) |