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(pī′rō-plăzm) A sporozoan protozoan of the subclass Piroplasia, such as the genus Babesia.


(pī′sĭ-form″) [L. pisum, pea + -form] 1. Pea-shaped. 2. The smallest carpal bone, located in the flexor carpi ulnaris tendon as a sesamoid bone, on the ulnar side in the proximal row of carpals.


(pis′tŏn-ing) The vertical displacement of a prosthetic socket on an amputated limb, evident as an up-anddown movement of the prosthesis during gait. It is caused by loosening of the socket and/or inadequate suspension.


(pit) 1. A tiny hollow or pocket. SYN: depression; fossa. 2. To be or become marked with a shallow depression. 3. To cause a depression on pressure in edema. 4. A small depression in the enamel surface of a tooth often connected with one or more developmental grooves. It contributes to pit and fissure caries. SYN: occlusal p.

anal p. Proctodeum.

gastric p. Any of many pits in the gastric mucosa into which the gastric glands open. SEE: illus.





nasal p. In the embryo, one of two horseshoe-shaped pits on the ventrolateral surface of the head bounded by lateral and median nasal processes. It gives rise to nostrils and a portion of the nasal fossa. SYN: olfactory p.

occlusal p. Pit (3).

olfactory p. Nasal p.

optic pit A small pit of the optic nerve head. It may sometimes release fluid below the retina, which can cause central retinal detachment.

primitive p. A minute pit at the anterior end of the primitive groove or streak and immediately posterior to the primitive knot. SEE: primitive groove; primitive node; primitive streak.

p. of the stomach 1. A colloquial term for the depression at the end of the xiphoid process. 2. A colloquial term for the center of the abdominal region above the navel.


(pich) [Middle English pichen fr Old English piccean, pīcian, to prick] 1. That quality of sound that enables one to classify it in a scale from high to low. The pitch is dependent principally on frequency of vibrations. 2. In radiography, the table speed divided by the width of the x-ray beam.

beam p. In computed tomography, the table travel per each spiral rotation of the x-ray beam divided by either the thickness of the detector rows or the collimation of the x-ray. SEE: table travel speed.


(pich) [Old ...

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