| inversion of chromosomes | A chromosome aberration resulting from a double break in a segment of the chromosome, with end for end rotation of the fragment between the fracture lines, and refusion of the fragments; this results in reversal of the order of genes in that segment. (05 Mar 2000) |
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| yeast artificial chromosomes | Yeast DNA sequences that have incorporated into them very large foreign DNA fragments; the recombinant DNA is then introduced into the yeast by transformation; the use of yeast artificial chromosomes permits the cloning of large genes with their flanking regulatory sequences. (05 Mar 2000) |
| abdominal ring | The opening in the transversalis fascia through which the ductus deferens (or round ligament in the female) and gonadal vessels enter the inguinal canal. Located midway between anterior superior iliac spine and pubic tubercle, it is bounded medially by the lateral umbilical ligament (inferior epigastric vessels) and inferiorly by the inguinal ligament. Indirect inguinal hernias exit the abdominal cavity via the deep inguinal ring Synonym: annulus inguinalis profundus, abdominal ring, annulus abdominalis, internal inguinal ring. (05 Mar 2000) |
| amnion ring | The ring formed by the attachment of the amnion to the umbilical cord at its point of emergence from the umbilicus. (05 Mar 2000) |
| annuloplasty ring | The dilated annulus is sutured, often to a prosthetic ring, thereby reducing it to its normal systolic size. (05 Mar 2000) |
| anterior limiting ring | The periphery of the cornea marking the termination of Descemet's membrane and the anterior border of the trabecular meshwork; an important landmark in gonioscopy. Synonym: Schwalbe's ring. (05 Mar 2000) |
| Balbani ring | An extremely large puff at a band of a polytene chromosome. (05 Mar 2000) |
| Balbiani ring | <cell biology, genetics> The largest puffs seen on the polytene chromosomes of Diptera are called Balbiani rings after the nineteenth century microscopist who first described polytene chromosomes. (18 Nov 1997) |
| Bandl's ring | A constriction located at the junction of the thinned lower uterine segment with the thick retracted upper uterine segment, resulting from obstructed labour; this is one of the classic signs of threatened rupture of the uterus. Synonym: Bandl's ring, Baudelocque's uterine circle, Scanzoni's second os. (05 Mar 2000) |
| benzene ring | The closed-chain arrangement of the carbon and hydrogen atoms in the benzene molecule. See: cyclic compound. (05 Mar 2000) |
| Bickel's ring | The broken ring of lymphoid tissue, formed of the lingual, faucial, and pharyngeal tonsils. Synonym: Bickel's ring, tonsillar ring, Waldeyer's throat ring. (05 Mar 2000) |
| Cabot's ring bodies | Ring-shaped or figure-of-eight structures that stain red with Wright's stain, found in red blood cells in severe anaemias, possibly a remnant of the nuclear membrane; a form of basophilic degenerative process. (05 Mar 2000) |
| Cannon's ring | The location in the mid-transverse colon at which innervation by superior and inferior mesenteric plexuses overlap at the junction of the primitive midgut and hindgut, frequently resulting in narrowing evident on barium enema. See: Cannon's ring. Synonym: Cannon's ring. (05 Mar 2000) |
| carcinoma, signet ring cell | A highly malignant, mucus-secreting tumour in which the mucus-secreting cells are anaplastic and appear rounded, with the nucleus displaced to one side by a globule of mucus in the cytoplasm. (12 Dec 1998) |
| cardiac lymphatic ring | A group of lymph nodes surrounding the cardia of the stomach. Synonym: annulus lymphaticus cardiae, cardiac lymphatic ring. (05 Mar 2000) |