| PPM | permanent pacemaker; phosphopentomutase; physician practice management; pigmented pupillary membrane... |
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| PPNAD | primary pigmented nodular adrenocortical disease |
| PRE | photoreacting enzyme; physician's report of examination; pigmented retinal epithelium; preplacement ... |
| PVNS | pigmented villonodular synovitis |
| HVL | Half-Value Layer |
| central artery of retina | A branch of the ophthalmic artery which penetrates the optic nerve 1 cm behind the eye to enter the eye at the optic papilla in the retina; it divides into superior and inferior temporal and nasal branches. Synonym: arteria centralis retinae, arteria retinae centralis, Zinn's artery. (05 Mar 2000) |
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| central vein of retina | Formed by union of the retinal veins and accompanies the artery of the same name in the optic nerve. Synonym: vena centralis retinae. (05 Mar 2000) |
| retina | Light sensitive layer of the eye. In vertebrates, looking from outside, there are four major cell layers: (i) the outer neural retina, which contains neurons (ganglion cells, amacrine cells, bipolar cells) as well as blood vessels, (ii) the photoreceptor layer, a single layer of rods and cones, (iii) the pigmented retinal epithelium (PRE or RPE), (iv) the choroid, composed of connective tissue, fibroblasts and including a well vascularised layer, the chorio capillaris, underlying the basal lamina of the PRE. Behind the choroid is the sclera, a thick organ capsule. In molluscs (especially cephalopods such as the squid) the retina has the light sensitive cells as the outer layer with the neural and supporting tissues below. See: retinal rods, retinal cones, rhodopsin. (18 Nov 1997) |
| retina-specific amine oxidase | <enzyme> Genbank d88213 Registry number: EC 1.4.- Synonym: rao enzyme, human (26 Jun 1999) |
| granular layers of retina | The outer nuclear layer, layer 4, of the retina, neuroepithelial layer of retina, and the inner layer, layer 6, of the retina, ganglionic layer of retina. Synonym: granular layers of retina, stratum nucleare externum et internum retinae. (05 Mar 2000) |
| rivalry of retina | Simultaneous excitation of corresponding retinal areas of each eye by stimuli that differ in size, colour, shape, or luminance, making fusion impossible. (05 Mar 2000) |
| rod cell of retina | 1. A straight and slender stick; a wand; hence, any slender bar, as of wood or metal (applied to various purposes). Specifically: An instrument of punishment or correction; figuratively, chastisement. "He that spareth his rod hateth his son." (Prov. Xiii. 24) A kind of sceptor, or badge of office; hence, figuratively, power; authority; tyranny; oppression. "The rod, and bird of peace." . A support for a fishing line; a fish pole. <machinery> A member used in tension, as for sustaining a suspended weight, or in tension and compression, as for transmitting reciprocating motion, etc.; a connecting bar. An instrument for measuring. 2. A measure of length containing sixteen and a half feet; called also perch, and pole. Black rod. <anatomy> Rods and cones, the elongated cells or elements of the sensory layer of the retina, some of which are cylindrical, others somewhat conical. Origin: The same word as rood. See Rood. Source: Websters Dictionary (01 Mar 1998) |
| rods (retina) | One of the two photoreceptor cell types of the vertebrate retina. In rods the photopigment is in stacks of membranous disks separate from the outer cell membrane. Rods are more sensitive to light than cones, but rod mediated vision has less spatial and temporal resolution than cone vision. (12 Dec 1998) |
| gyrate atrophy of choroid and retina | A slowly progressive atrophy of the choriocapillaris, pigmentary epithelium, and sensory retina, with irregular confluent atrophic areas and an associated ornithinuria; autosomal recessive inheritance; due to a deficiency of ornithine d-aminotransferase. (05 Mar 2000) |
| ciliary part of retina | ciliary part of retina |
| coarctate retina | An obsolete term for a ringlike effusion of fluid between the choroid and retina, giving the latter a funnel shape. (05 Mar 2000) |
| pigment cells of retina | Cell's in the outermost layer of the retina that contain pigment granules. (05 Mar 2000) |
| pigment epithelium of optic retina | pigmented part of retina |
| cone cell of retina | 1. <plant biology> In gymnosperms and club mosses, a group of sporophylls arranged compactly on a central axis, in the angiosperm family Casuarina, a woody multiple fruit incorporating the bracts and bracteoles associated with the flowers. 2. <physiology> The retinal cone responsible for colour vision. (03 Jul 1999) |
| plexiform layers of retina | Layer's of the retina where synapses occur; in the external layer, processes of rods and cones synapse with bipolar neuron dendrites; in the internal layer, axon terminals of bipolar cells synapse with ganglion cell dendrites. See: retina. Synonym: stratum plexiforme externum et internum retinae. (05 Mar 2000) |