1. A patch or small differentiated area on a body surface (e.g., skin, mucosa, or arterial endothelium) or on the cut surface of an organ such as the brain. 2. An area of clearing in a flat confluent growth of bacteria or tissue cells, such as is caused by the lytic action of bacteriophage in an agar plate culture of bacteria, by the cytopathic effect of certain animal viruses in a sheet of cultured tissue cells, or by antibody (hemolysin) produced by lymphocytes cultured in the presence of erythrocytes and to which complement has been added. 3. A sharply defined zone of demyelination characteristic of multiple sclerosis. 4. See dental p. [Fr. a plate]
atheromatous p. a well-demarcated yellow area or swelling on the intimal surface of an artery; produced by intimal lipid deposit.
bacterial p. in dentistry, a mass of filamentous microorganisms and large variety of smaller forms attached to the surface of a tooth which, depending on bacterial activity and environmental factors, may give rise to caries, calculus, or inflammatory changes in adjacent tissue.dental p. (2), mucous p., mucinous p;
bacteriophage p. a clear circular zone in an otherwise confluent growth of bacteria on an agar surface resulting from bacterial lysis by bacterial viruses.
dental p. 1. the noncalcified accumulation mainly of oral microorganisms and their products, that adheres tenaciously to the teeth and is not readily dislodged; 2. bacterial p
Hollenhorst p.'s glittering, orange-yellow, atheromatous emboli in the retinal arterioles that contain cholesterin crystals and originate in the carotid artery or great vessels.
mucous p. , mucinous p. bacterial p
neuritic p. senile p
pleural p. fibrous thickening of the parietal pleura, characteristically caused by inhalation exposure to asbestos.
Randall's p.'s mineral concentrations of renal papillae.
senile p. a spherical mass comprised primarily of amyloid fibrils and interwoven neuronal processes, frequently, although not exclusively, observed in Alzheimer's disease.neuritic p;
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