| pyrrole ring | <biochemistry, chemistry> A heterocyclic ring structure, found in many important biological pigments and structures that involve an activated metal ion, for example chlorphyll, hem. (18 Nov 1997) |
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| signet ring | The early stage of trophozoite development of the malaria parasite in the red blood cell; the parasite cytoplasm stains blue around its circular margin, and the nucleus stains red in Romanowsky stains, while the central vacuole is clear, giving the ringlike appearance. (05 Mar 2000) |
| 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) |
| 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) |
| superficial inguinal 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) |
| deep inguinal 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) |
| Imlach's ring | That part of the inguinal canal which lodges the round ligament of the uterus. (05 Mar 2000) |
| internal inguinal 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) |
| 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) |