| signet-ring cell carcinoma | <tumour> A poorly differentiated adenocarcinoma composed of cells with a cytoplasmic droplet of mucus that compresses the nucleus to one side along the cell membrane; arises most frequently in the stomach, occasionally in the large bowel or elsewhere. (05 Mar 2000) |
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| signet ring cells | Altered basophilic cells of the anterior lobe of the pituitary that develop following castration; the body of the cell is occupied by a large vacuole that displaces the nucleus to the periphery, giving the cell a resemblance to a signet ring. Synonym: signet ring cells. (05 Mar 2000) |
| S ring | <molecular biology> The static part of the bacterial motor: a ring of 15 or 17 sub units (one or less more than the M ring), anchored to the inner surface of the cell wall. (10 Mar 1998) |
| neonatal ring | In deciduous teeth, a line of demarcation between prenatal and postnatal enamel. Synonym: neonatal ring. (05 Mar 2000) |
| subcutaneous ring | The slit-like opening in the aponeurosis of the external oblique muscle of the abdominal wall through which the spermatic cord (round ligament in the female) and inguinal hernias emerge from the inguinal canal. See: aponeurosis of external abdominal oblique muscle. Synonym: annulus inguinalis superficialis, external inguinal ring, subcutaneous ring. (05 Mar 2000) |
| Imlach's ring | That part of the inguinal canal which lodges the round ligament of the uterus. (05 Mar 2000) |
| oesophageal ring | A congenital anatomic narrowing in the lower 1/3 of the oesophagus that is the result of inappropriate embryological development of the oesophagus. Symptoms include difficulty swallowing and chest pain (under the sternum). Treatment involves the use of a fibreoptic endoscope using a dilator to open up the narrowed segment of the oesophagus. (27 Sep 1997) |
| oesophagogastric ring | A congenital anatomic narrowing in the lower 1/3 of the oesophagus that is the result of inappropriate embryological development of the oesophagus. Symptoms include difficulty swallowing and chest pain (under the sternum). Treatment involves the use of a fibreoptic endoscope using a dilator to open up the narrowed segment of the oesophagus. (27 Sep 1997) |
| tonsillar 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) |
| tracheal ring | The 16 to 20 incomplete rings of hyaline cartilage forming the skeleton of the trachea; the rings are deficient posteriorly for from one-fifth to one-third of their circumference. Synonym: cartilagines tracheales, tracheal ring. (05 Mar 2000) |
| tympanic ring | In the foetus, a more or less complete bony ring at the medial end of the cartilaginous external acoustic meatus, to which is attached the tympanic membrane. Synonym: annulus tympanicus, tympanic bone. (05 Mar 2000) |
| UDPglucose-flavonol-ring-B-O-glucosyltransferase | <enzyme> Transfers glucose from udpg to positions 2' or 5' of partially methylated flavonols Registry number: EC 2.4.1.- Synonym: flavonol-ring-b o-glucosyltransferase, flavonol rbo glucosyltransferase, flavonol ring-beta-o-glucosyltransferase (26 Jun 1999) |
| Kayser-Fleischer ring | A greenish yellow pigmented ring encircling the cornea just within the corneoscleral margin, seen in hepatolenticular degeneration, due to copper deposited in Descemet's membrane. Synonym: Fleischer-Strumpell ring. (05 Mar 2000) |
| umbilical ring | An opening in the linea alba through which pass the umbilical vessels in the foetus; in young embryos it is relatively nearer to the pubis, but gradually ascends to the centre of the abdomen; it is closed in the adult, its site being indicated by the umbilicus or navel. Synonym: annulus umbilicalis, canalis umbilicalis. (05 Mar 2000) |
| Zinn's ring | A fibrous ring that surrounds the optic canal and the medial part of the superior orbital fissure; it gives origin to the four rectus muscles of the eye and is partially fused with the sheath of the optic nerve. Synonym: annulus tendineus communis, Zinn's ligament, Zinn's ring, Zinn's tendon. (05 Mar 2000) |