| neural tube defect | <neurology, paediatrics> Abnormal development during embryonic life of the neural tube producing congenital malformations of the nervous system due to closure failure of the neural tube. The structure gives rise to the central nervous system (the brain and spinal cord), and failure to close results in anencephaly (absence of the cranial vault and absence of most or all of the cerebral hemispheres of the brain) and spina bifida or meningomyelocele (open spina with exposure and protusion of the spinal cord). The risk of neuroal tube defects can be decreased by the mother taking folic acid during pregnancy. (04 Jul 1999) |
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| dorsal plate of neural tube | The thin layer of the embryonic neural tube connecting the alar plate's dorsally. Synonym: dorsal plate of neural tube. (05 Mar 2000) |
| dorsolateral plate of neural tube | 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) |
| ganglion cells of retina | The nerve cell's of the retina whose central processes (fibres) form the optic nerve; their peripheral processes synapse with the bipolar cell's and through them with the rod and cone cell's; these cell bodies are round or flask-shaped and vary considerably in size. (05 Mar 2000) |
| ganglionic layer of retina | The intermediate layer of neurons in the retina composed largely of bipolar cells. Synonym: internal nuclear layer of retina, stratum ganglionare retinae, stratum nucleare internum retinae. (05 Mar 2000) |
| medial arteriole of retina | An arteriole supplying the part of the retina between the optic disk and the macula. Synonym: arteriola medialis retinae. (05 Mar 2000) |
| medial venule of retina | The small vein that passes from the part of the retina between the macula and the optic disk to join the central vein. Synonym: venula medialis retinae. (05 Mar 2000) |
| 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) |
| 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) |
| cerebral layer of retina | The internal layer of the retina containing the neural elements, as distinguished from the outer leaf of the retina, or pigmented layer. Synonym: pars optica retinae, neural layer of retina, optic part of retina, stratum cerebrale 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) |