| optic layer | A layer of white matter interspersed with nerve-cell bodies, immediately below the superficial gray layer of the superior colliculus, composed of myelinated fibres originating in the retina and striate cortex, the inner layer of the retina, consisting of the fibres originating from the cells of the ganglionic layer of optic nerve; in their further course these fibres combine to form the optic nerve or optic tract. Synonym: stratum opticum. (05 Mar 2000) |
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| orbital layer of ethmoid bone | A thin plate of ethmoid bone forming part of the medial wall of the orbit and the lateral wall for the ethmoidal labyrinth. Synonym: lamina orbitalis ossis ethmoidalis, lamina papyracea, orbital lamina of ethmoid bone, orbital layer of ethmoid bone, orbital plate, paper plate, papyraceous plate. (05 Mar 2000) |
| osteogenetic layer | The inner bone-forming layer of the periosteum. (05 Mar 2000) |
| tenth-value layer | <radiobiology> Thickness of a specified substance which, when introduced into the path of a given beam of radiation, reduces the absorbed dose index or dose-equivalent index to one-tenth. The magnitude of the tenth-value layer may be different for absorbed dose index and dose equivalent index. (16 Dec 1997) |
| thin layer chromatography | <technique> Chromatography using a thin layer of powdered medium on an inert sheet to support the stationary phase. Faster than paper chromatography, gives higher resolution and requires smaller samples. (18 Nov 1997) |
| thin-layer chromatography | Chromatography through a thin layer of cellulose or similar inert material supported on a glass or plastic plate. (05 Mar 2000) |
| thin-layer electrophoresis | Electrophoretic migrations (separations) through a thin layer of inert material, such as cellulose, supported on a glass or plastic plate. (05 Mar 2000) |
| thin-layer immunoassay | A method for detection of antigen-antibody reactions, applicable to detection of either antigen or antibody, based on the fact that either reactant, when added to a polystyrene surface (such as a well in a polystyrene plate) is adsorbed as a thin layer and acts as an immunosorbent capable of binding with the second reactant. (05 Mar 2000) |
| e-layer | <radiobiology> Cylinder of relativistic electrons gyrating in a magnetic field, which produces a self-field strong enough to dominate the externally applied field and produce a field-reversal (where the B field changes sign) in the system. See: Field-Reversed Configuration, Field-Reversed Pinch. (09 Oct 1997) |
| Tomes' granular layer | <dentistry> A thin layer of dentin adjacent to the cementum, appearing granular in ground sections; the granules are small uncalcified spaces. (05 Mar 2000) |
| enamel layer | The internal layer of the enamel organ. Synonym: enamel layer. (05 Mar 2000) |
| ependymal layer | An inner epithelial layer of cells bordering the lumen of the embryonic neural tube and brain, formed during the latter's stratification, and persisting in modified form throughout life. Synonym: ependymal zone, ventricular layer. (05 Mar 2000) |
| epithelial choroid layer | The layer of modified ependymal cells that forms the inner layer of the tela choroidea, facing the ventricle. Synonym: lamina epithelialis, epithelial choroid layer, lamina choroidea epithelialis, lamina choroidea. (05 Mar 2000) |
| epitrichial layer | The superficial flattened-cell layer of the epidermis of a young embryo before the definitive stratification has developed. (05 Mar 2000) |
| external nuclear layer of retina | The outermost layer of the cerebral layer of retina, composed of the primary receptor cells of the retina; the stratum consists of two sublayers: 1) an external layer made up of the rods and cones, the photosensitive processes of the receptor cells, and 2) the external nuclear layer containing the cell bodies of these cells; the external limiting membrane forms a perforated supporting plate between the two sublayers; the name refers to the fact that the retinal receptor cells are a specialised form of (epithelial) ependyma cell and thus, in a sense, are comparable to the neuroepithelial cells (e.g., hair cells) of other sense organs. Synonym: external nuclear layer of retina, stratum neuroepitheliale retinae, stratum nucleare externum retinae. (05 Mar 2000) |