| 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) |
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| 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) |
| segmentectomy | Excision of a segment of any organ or gland. (05 Mar 2000) |
| segmented cell | A polymorphonuclear leukocyte matured beyond the band cell so that two or more lobes of the nucleus occur. (05 Mar 2000) |
| segmented leukocyte | Any mature polymorphonuclear leukocyte, especially a neutrophilic leukocyte. (05 Mar 2000) |
| segmented neutrophil | A fully matured neutrophil that has at least 2 (and as many as 5) distinct lobes in the nucleus and manifests active ameboid motion. Synonym: mature neutrophil. (05 Mar 2000) |
| segmenter | A schizont; usually applied to the malaria parasite developing in a red blood cell after having undergone nuclear and cytoplasmic division, just before cell rupture and release of the merozoites. (05 Mar 2000) |
| Segmentina | A genus of freshwater pulmonate snails (family Planorbidae, subfamily Segmentininae); includes the species Segmentina hemisphaerula, an important intermediate host of Fasciolopsis buski. Origin: L. Segmentum, fr. Seco, to cut (05 Mar 2000) |
| segmenting body | A sporozoan trophozoite (vegetative form) that reproduces by schizogony, producing a varied number of daughter trophozoites or merozoites. See: meront, segmenter. Synonym: agamont, segmenting body. Origin: schizo-+ G. On (ont-), a being (05 Mar 2000) |
| segments of liver | Territories of the liver with independent portobilioarterial distribution or independent venous drainage. The naming of segments in the NA is based upon the portobilioarterial distribution. See: anterior segment, lateral segment, medial segment, posterior segment. Synonym: segmenta hepatis, segments of liver. (05 Mar 2000) |
| segments of spinal cord | Portions of the spinal cord corresponding to the line of attachment of the roots of the individual spinal nerves. These are the cervical spinal cord segments [C1-C8]; the thoracic spinal cord segments [T1-T12]; the lumbar spinal cord segments Origin: L1-L5]; the sacral spinal cord segments [S1-S5]; and the coccygeal spinal cord segments [Co1-Co3]. Synonym: segmenta medullae spinalis. (05 Mar 2000) |
| segments of spleen | Splenic territories receiving independent arterial supply or drained by independent roots of the splenic vein. Synonym: segmenta lienis. (05 Mar 2000) |
| segmentum | Synonym: segment. Origin: L. Segment (05 Mar 2000) |
| segmentum anterius | A delimited part or section of an organ or other structure which lies in front of or ventral to the other similar parts or sections. 1) segmentum anterius (hepar); the anterior segment of the right lobe of the liver. 2) segmentum anterius (pulmo dexter et sinister); [S 3]; the anterior segment of the superior lobe of the right and left lungs. 3) anterior segment of the eye; the intraocular segment of the eyeball occupied by the aqueous which lies in front of, and is separated from the vitreous-filled posterior segment by, the lens and zonule; it is subdivided by the iris into anterior and posterior chambers. Synonym: segmentum anterius. (05 Mar 2000) |
| subapical segment | An inconstant segment of the inferior lobe of the right and left lungs. Synonym: segmentum subapicale, segmentum subsuperius, subsuperior segment. (05 Mar 2000) |
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| subsuperior segment | An inconstant segment of the inferior lobe of the right and left lungs. Synonym: segmentum subapicale, segmentum subsuperius, subsuperior segment. (05 Mar 2000) |
| superior lingular segment | Superior lingular segment of the superior lobe of the left lung; lies above inferior lingular segment. Synonym: segmentum lingulare superius. (05 Mar 2000) |
| superior segment | The uppermost segment of the kidney. Synonym: apical segment. (05 Mar 2000) |
| sympathetic segment | A divison of the sympathetic trunks based on the origins of the gray communicating branches. (05 Mar 2000) |
| D gene segment | <molecular biology> Diversity gene segment. Part of the gene for the immunoglobin heavy chain, it codes for part of the hypervariable region of the VH domain and is located between the VH and JH segments. There are probably about 20 different D segments. (18 Nov 1997) |
| inferior lingular segment | Inferior lingular segment of superior lobe of left lung; between superior lingular segment and oblique fissure. Synonym: segmentum lingulare inferius. (05 Mar 2000) |
| inferior segment of kidney | Which typically consists of approximately the inferior third of the kidney viewed either anteriorly or posteriorly. Synonym: segmentum inferius. (05 Mar 2000) |
| interannular segment | The portion of a myelinated nerve fibre between two successive nodes. Synonym: interannular segment, internode, Ranvier's segment, segmentum internodale. (05 Mar 2000) |
| intermaxillary segment | The primordial mass of tissue formed by the merging of the medial nasal prominences of the embryo; it contributes to the intermaxillary portion of the upper jaw, the prolabial portion of the upper lip, and the primary palate. (05 Mar 2000) |
| internodal segment | The portion of a myelinated nerve fibre between two successive nodes. Synonym: interannular segment, internode, Ranvier's segment, segmentum internodale. (05 Mar 2000) |
| joining segment | <molecular biology> A small DNA segment that links genes to yield a functional gene encoding an immunoglobulin. (09 Oct 1997) |
| upper uterine segment | The main portion of the body of the gravid uterus, the contraction of which furnishes the chief force of expulsion in labour. (05 Mar 2000) |
| lateral basal segment | Lateral basal segment of inferior lobe of right and left lung; between anterior and posterior basal segments. Synonym: segmentum basale laterale. (05 Mar 2000) |
| lateral segment | A delimited part or section of an organ or other structure which lies farthest to the left or right side of the other similar parts or sections. 1) segmentum laterale (hepar); the lateral segment of the left lobe of the liver. 2) segmentum laterale (pulmo dexter); [S 4]; the lateral segment of the middle lobe of the right lung. Synonym: segmentum laterale. (05 Mar 2000) |