| platelet transfusion | The transfer of blood platelets from a donor to a recipient or reinfusion to the donor. (12 Dec 1998) |
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| platelet-activating factor | <cytokine> Potent phospholipid activator and mediator of many leucocyte functions, including platelet aggregation, inflammation, and anaphylaxis. It is produced in response to specific stimuli by a variety of cell types, including neutrophils, basophils, platelets, and endothelial cells. Several molecular species of platelet-activating factor have been identified which vary in the length of the O-alkyl side chain. It is an important mediator of bronchoconstriction. Synonym: platelet-aggregating factor. Acronym: PAF (20 Sep 2002) |
| platelet-aggregating factor | <cytokine> Potent phospholipid activator and mediator of many leucocyte functions, including platelet aggregation, inflammation, and anaphylaxis. It is produced in response to specific stimuli by a variety of cell types, including neutrophils, basophils, platelets, and endothelial cells. Several molecular species of platelet-activating factor have been identified which vary in the length of the O-alkyl side chain. It is an important mediator of bronchoconstriction. Synonym: platelet-aggregating factor. Acronym: PAF (20 Sep 2002) |
| platelet-derived growth factor | <growth factor> The major mitogen in serum for growth in culture of cells of connective tissue origin. It consists of 2 different but homologous polypeptides A and B (~30,000 D) linked by disulphide bonds. Believed to play a role in wound healing. It is carried in the alpha-granules of platelets and is released when platelets adhere to traumatised tissues. Connective tissue cells near the traumatised region respond by initiating the process of replication. The B chain is almost identical in sequence to p28sis, the transforming protein of simian sarcoma virus, that can transform only those cells that express receptors for platelet derived growth factor, suggesting that transformation is caused by autocrine stimulation. The receptor is a tyrosine kinase. Acronym: PDGF (12 Dec 1998) |
| plateletpheresis | The preparation of platelet concentrates with the return of red cells and platelet-poor plasma to the donor. (12 Dec 1998) |
| platelets | A particle found in the bloodstream that binds to fibrinogen at the site of a wound to begin the blood clotting process. Platelets are formed in bone marrow, where they arise from cells called megakaryocytes. (09 Oct 1997) |
| platelike atelectasis | Collapse of the portion of the lung distal to an obstructed subsegmental bronchus, manifested as a linear opacity on a chest radiograph. See: Fleischner lines. Synonym: platelike atelectasis. (05 Mar 2000) |
| platetrope | <anatomy> One of a pair of a paired organs. Origin: Gr. Breadth + to turn. Source: Websters Dictionary (01 Mar 1998) |
| phase plate | <microscopy> The plate used near the back focal plane of a microscope objective lens (in conjunction with an annulus at the front focal plane of the condenser lens) to achieve phase contrast. The phase plate selectively shifts the phase of the waves diffracted by the specimen by a quarter wave and reduces the amplitude of the undeviated, direct beam. (05 Aug 1998) |
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| phosphor plate | The coated plate used in place of a radiographic film cassette in a computed radiography system. (05 Mar 2000) |
| miniature end plate potential | <physiology> Small fluctuations (typically 0.5 mV) in the resting potential of postsynaptic cells. They are the same shape as, but much smaller than, the end plate potentials caused by stimulation of the presynaptic cell. Miniature end plate potentials are considered as evidence for the quantal release of neurotransmitters at chemical synapses, a single miniature end plate potential resulting from the release of the contents of a single synaptic vesicle. (12 Jan 1998) |
| cloacal plate | A plate, composed of a layer of cloacal endoderm in contact with a layer of proctodeal ectoderm, which subsequently ruptures, forming the anal and urogenital openings of the embryo. (05 Mar 2000) |
| comb plate | <cell biology> Large flat organelles formed by the fusion of many cilia. Vertical rows of comb plates form the motile appendages of Ctenophores. (18 Nov 1997) |
| motor plate | A motor endplate. (05 Mar 2000) |
| wing plate | The dorsal division of the lateral walls of the neural tube in the embryo; it gives rise to neurons relaying afferent impulses to higher centres; in the adult such neurons compose the sensory nuclei of the spinal cord and brainstem. Synonym: lamina alaris, alar plate of neural tube, dorsolateral plate of neural tube, lamina dorsalis, wing plate. (05 Mar 2000) |
| muscle plate | <anatomy> A muscular segment; one of the zones into which the muscles of the trunk, especially in fishes, are divided; a myocomma. One of the embryonic muscular segments arising from the protovertebrae; also, one of the protovertebrae themselves. The muscular system of one metamere of an articulate. See: Myotomy. Source: Websters Dictionary (01 Mar 1998) |
| cribriform plate of ethmoid bone | A horizontal lamina from which are suspended the labyrinth, on either side, and the lamina perpendicularis in the centre; it fits into the ethmoidal notch of the frontal bone and supports the olfactory lobes of the cerebrum, being pierced with numerous openings for the passage of the olfactory nerves. Synonym: lamina cribrosa ossis ethmoidalis, cribrum, sieve bone, sieve plate. (05 Mar 2000) |
| cutis plate | The area of skin innervated by a single posterior spinal nerve (sensory nerve). (27 Sep 1997) |
| prechordal plate | A small area immediately rostral to the cephalic tip of the notochord where ectoderm and endoderm are in contact; when turned under the growing head, it forms the pharyngeal membrane. See: oral plate. Synonym: prechordal plate. (05 Mar 2000) |
| prochordal plate | A small area immediately rostral to the cephalic tip of the notochord where ectoderm and endoderm are in contact; when turned under the growing head, it forms the pharyngeal membrane. See: oral plate. Synonym: prechordal plate. (05 Mar 2000) |
| Salter-Harris classification of epiphysial plate injuries | The classification of epiphysial plate injuries into five groups (I to V), according to the pattern of damage to epiphysis, physis, and/or metaphysis; the classification correlates with different prognoses regarding the effects of the injury on subsequent growth and subsequent deformity of the epiphysis. (05 Mar 2000) |
| secondary spiral plate | A ridge on the outer wall of the first turn of the cochlea opposite the spiral lamina. Synonym: lamina spiralis secundaria, secondary spiral plate. (05 Mar 2000) |
| segmental plate | In a young embryo, the thickened dorsal portion of the undifferentiated paraxial mesoderm which becomes metamerically divided to form the mesodermal somites. Synonym: segmental plate. (05 Mar 2000) |