| MDS | Master of Dental Surgery; maternal deprivation syndrome; medical data screening; medical data system... |
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| MPD | main pancreatic duct; maximum permissible dose; mean population doubling; membrane potential differe... |
| NLD | nasolacrimal duct; necrobiosis lipoidica diabeticorum |
| PCD | pacer-cardioverter-defibrillator; papillary collecting duct; paraneoplastic cerebellar degeneration;... |
| PD | Doctor of Pharmacy; Dublin Pharmacopoeia; interpupillary distance; Paget disease; pancreatic duct; p... |
| long-terminal repeat | <molecular biology> Identical DNA sequences, several hundred nucleotides long, found at either end of transposons and the proviral DNA, formed by reverse transcription of retroviral RNA. They are thought to have an essential role in integrating the transposon or provirus into the host DNA. Long terminal repeats have inverted repeats, that is, sequences close to either end are identical when read in opposite directions. In proviruses the upstream long-terminal repeat acts as a promoter and enhancer and the downstream long-terminal repeat as a polyadenylation site. Acronym: LTR (15 Nov 1997) |
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| long terminal repeat sequences | Regions of the RNA genome associated with regulation, integration, and expression of retroviruses. (05 Mar 2000) |
| abdominal part of thoracic duct | The part of the thoracic duct between the cisterna chyli and the aortic hiatus of the diaphragm. Synonym: pars abdominalis ductus thoracici. (05 Mar 2000) |
| accessory pancreatic duct | The excretory duct of the head of the pancreas, one branch of which joins the pancreatic duct, the other opening independently into the duodenum at the lesser duodenal papilla. Synonym: ductus pancreaticus accessorius, Bernard's canal, Bernard's duct, ductus dorsopancreaticus, Santorini's canal, Santorini's duct. (05 Mar 2000) |
| adenoma, bile duct | A benign tumour of the intrahepatic bile ducts. (12 Dec 1998) |
| alveolar duct | The part of the respiratory passages distal to the respiratory bronchiole; from it arise alveolar sacs and alveoli, the smallest of the intralobular duct's in the mammary gland, into which the secretory alveoli open. Synonym: ductulus alveolaris. (05 Mar 2000) |
| alveolar duct emphysema | Emphysema in which the primary involvement is in the alveolar ducts and respiratory bronchioles, as opposed to panacinar emphysema. (05 Mar 2000) |
| amniotic duct | The transitory opening between the seroamniotic folds in birds just before they fuse to form the seroamniotic raphe. (05 Mar 2000) |
| ampulla of milk duct | A circumscribed spindle-shaped dilation of the lactiferous duct just before it enters the nipple. In nursing mothers this dilatation stores a droplet of milk which is expressed by compression as the infant begins to suckle; this is thought to encourage continual suckling while the let-down reflex ensues. Synonym: sinus lactiferi, ampulla lactifera, ampulla of milk duct, lactiferous ampulla. (05 Mar 2000) |
| arch of thoracic duct | See: thoracic duct. (05 Mar 2000) |
| arterial duct | Before birth, the blood headed from the heart (via the pulmonary artery) for the lungs is shunted away from the lungs and returned to the greatest of arteries (the aorta). The shunt is through a short vessel called the ductus arteriosus. When the shunt is open, it is said to be patent (pronounced pa'tent). The patent ductus arteriosus (PDA) usually closes at or shortly after birth and blood is permtted from that moment on to course freely to the lungs. If the ductus stays open (patent), flow reverses and blood from the aorta is shunted into the pulmonary artery and recirculated through the lungs. The PDA may close later spontaneously (on its own) or need to be ligated (tied off) surgically. (12 Dec 1998) |
| Bartholin's duct | The duct that drains the anterior portion of the sublingual gland; it opens at the sublingual papilla. Synonym: ductus sublingualis major, Bartholin's duct. (05 Mar 2000) |
| basal lamina of saemicircular duct | The basal membrane underlying the epithelium of the saemicircular duct. Synonym: membrana basalis ductus saemicircularis, basal lamina of saemicircular duct. (05 Mar 2000) |
| basal membrane of saemicircular duct | The basal membrane underlying the epithelium of the saemicircular duct. Synonym: membrana basalis ductus saemicircularis, basal lamina of saemicircular duct. (05 Mar 2000) |
| basilar crest of cochlear duct | An inward projection of the spiral ligament of the cochlea to which is attached the basilar membrane forming the floor of the cochlear duct. Synonym: crista basilaris ductus cochlearis. (05 Mar 2000) |