| OAR | organ at risk |
|---|---|
| OBF | organ blood flow |
| OC | obstetrical conjugate; occlusocervical; office call; on call; only child; optic chiasma; oral contra... |
| OPO | Organ Procurement Organization |
| OS | left eye [Lat. oculus sinister]; occipitosacral; occupational safety; office surgery; Omenn syndrome... |
| enamel organ | Epithelial cells surrounding the dental papilla and differentiated into three layers: the inner enamel epithelium, consisting of ameloblasts which eventually form the enamel, and the enamel pulp and external enamel epithelium, both of which atrophy and disappear before and upon eruption of the tooth, respectively. (12 Dec 1998) |
|---|---|
| end organ | The special structure containing the terminal of a nerve fibre in peripheral tissue such as muscle, tissue, skin, mucous membrane, or glands. See: ending. (05 Mar 2000) |
| Jacobson's organ | A specialised part of the olfactory system located anteriorly in the nasal cavity within the nasal septum. Chemosensitive cells of the vomeronasal organ project via the vomeronasal nerve to the accessory olfactory bulb. The primary function of this organ appears to be in sensing pheromones which regulate reproductive and other social behaviours. While the structure has been thought absent in higher primate adults, data now suggests it may be present in adult humans. (12 Dec 1998) |
| floating organ | An organ with loose attachments, permitting its displacement. Synonym: floating organ, ptotic organ. (05 Mar 2000) |
| flower-spray organ of Ruffini | One of the two types of sensory nerve ending associated with the neuromuscular spindle (the other being the annulospiral ending); in this type, the fibre branches spread out upon the surface of the intrafusal fibres like a spray of flowers. Synonym: flower-spray organ of Ruffini. (05 Mar 2000) |
| foetal organ maturity | <embryology> Functional competence of specific foetal organs or body systems. In humans, it is usually assessed by analysis of amniotic fluid, as in the assessment of foetal lung maturity by analysis for components of pulmonary surfactant. (08 Mar 2000) |
| lateral line sense organ | A structure in fish consisting of a long groove or canal extending along each side of the trunk and tail and branching in the head region; the groove or tube is lined with neuroepithelial cells, some of which are in groups known as neuromasts; its function appears to be the detection of vibrations of low frequency. Synonym: neuromast organ. (05 Mar 2000) |
| abdominal | <anatomy> Pertaining to the abdomen. Origin: L. Abdominalis (18 Nov 1997) |
| abdominal abscess | <surgery> A localised pus-forming (suppurative) bacterial infection that occurs within the abdominal cavity as the result of a perforated viscus or post operative complication. Treatment requires either percutaneous or open surgical drainage. (27 Sep 1997) |
| abdominal adhesions | <surgery> Scarring that can occur within the abdomen in response to surgery or chronic inflammation. (27 Sep 1997) |
| abdominal angina | <surgery> A dull, crampy centralised abdominal pain that occurs 15-30 minutes after a meal. Associated with ischaemic bowel disease. Evaluated with mesenteric arteriography. (27 Sep 1997) |
| abdominal aorta | <anatomy> The largest arterial conduit below the diaphragm. This term refers to the portion of the aorta below the diaphragm to the bifurcation into the right and left common iliac arteries. It supplies blood to the abdominal viscera, pelvic organs and lower extremities. (20 Jun 2000) |
| abdominal aortic aneurysm | <surgery> A distended and weakened area in the wall of the abdominal aorta, more common in those who suffer from atherosclerosis. Symptoms include sudden, severe abdominal pain with radiation to the back. (27 Sep 1997) |
| abdominal aortic coarctation | <radiology> 2% of all coarctations, (most common site is thoracic: just distal to origin of L SCA), may be isolated congenital anomaly, associated with: thoracic aortic coarctation, idiopathic hypercalcaemia syndrome, rubella syndrome (ToRCHS), Takayasu arteritis, neurofibromatosis, radiation therapy, fibromuscular disease (12 Dec 1998) |
| abdominal aortic plexus | <anatomy, neurology> An autonomic plexus surrounding the abdominal aorta, directly continuous with the thoracic aortic plexus above and continued inferior to the bifurcation of the aorta as the superior hypogastric plexus. Synonym: plexus aorticus abdominalis. (05 Mar 2000) |