| retardation plate | <optics> A plate placed in the path of a beam of polarized light for the purpose of introducing a difference in phase. Usually a quarter-wave plate and a first-order red plate are furnished with a polarizing microscope. See: quartz wedge, compensator. (10 Mar 1998) |
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| perpendicular plate | Flat portion of a bone which lies within or closely approximates a vertical plane. See: perpendicular plate of ethmoid bone, perpendicular plate of palatine bone. Synonym: lamina perpendicularis, pars perpendicularis, vertical plate. (05 Mar 2000) |
| perpendicular plate of ethmoid bone | A thin plate of bone projecting downward from the crista galli of the ethmoid; it forms part of the nasal septum. Synonym: lamina perpendicularis ossis ethmoidalis. (05 Mar 2000) |
| perpendicular plate of palatine bone | The part of the palatine bone that extends vertically upward from the horizontal lamina; it forms part of the lateral wall of the nasal cavity. Synonym: lamina perpendicularis ossis palatini. (05 Mar 2000) |
| metaphase plate | <cell biology> The plane of the spindle approximately equidistant from the two poles along which the chromosomes are lined up during mitosis or meiosis. Also termed the equator. (18 Nov 1997) |
| growth plate | <physiology> The area between the epiphysis and the diaphysis within which bone growth occurs. (12 Dec 1998) |
| chorionic plate | That portion of the chorionic wall in the region of its uterine attachment; it consists of the mesoderm that lines the chorionic vesicle and, on the maternal side, of the trophoblast that lines the intervillous spaces; in the last half of gestation, the mesodermal connective tissue is largely replaced by fibrinoid material, and the amniotic membrane is adherent to the foetal side of the plate. (05 Mar 2000) |
| roof plate | The thin layer of the embryonic neural tube connecting the alar plate's dorsally. Synonym: dorsal plate of neural tube. (05 Mar 2000) |
| 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) |
| 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) |