| smear layer | Adherent debris produced when cutting the enamel or dentin in cavity preparation. It is about 1 micron thick and its composition reflects the underlying dentin, although different quantities and qualities of smear layer can be produced by the various instrumentation techniques. Its function is presumed to be protective, as it lowers dentin permeability. However, it masks the underlying dentin and interferes with attempts to bond dental material to the dentin. (12 Dec 1998) |
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| somatic layer | The external layer of the lateral mesoderm of the embryo, lying adjacent to the ectoderm and together with it constituting the somatopleure. (05 Mar 2000) |
| spindle-celled layer | Layer 6 of the cortex cerebri. Synonym: multiform layer, polymorphous layer, spindle-celled layer. (05 Mar 2000) |
| spinous layer | The layer of polyhedral cells in the epidermis; shrinkage artifacts and adhesion of these cells at their desmosomal junctions gives a spiny or prickly appearance. Synonym: prickle cell layer, spinous layer. (05 Mar 2000) |
| splanchnic layer | The internal layer of the lateral mesoderm, lying adjacent to the endoderm and together with it forming the splanchnopleure. (05 Mar 2000) |
| still layer | The layer of the bloodstream in the capillary vessels, next to the wall of the vessel, that flows slowly and transports the white blood cells along the layer wall, while in the centre the flow is rapid and transports the red blood cells. Synonym: plasma layer, Poiseuille's space, sluggish layer. (05 Mar 2000) |
| neural layer of optic retina | See: retina. (05 Mar 2000) |
| neural 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) |
| neuroepithelial 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) |
| Nitabuch's layer | A layer of fibrin between the boundary zone of compact endometrium and the cytotrophoblastic shell in the placenta. Synonym: Nitabuch's layer, Nitabuch's stria. (05 Mar 2000) |
| subendocardial layer | The loose connective tissue layer that joins the endocardium and myocardium; in the ventricles, it contains branches of the conducting system of the heart. (05 Mar 2000) |
| subendothelial layer | The thin layer of connective tissue lying between the endothelium and elastic lamina in the intima of blood vessels. (05 Mar 2000) |
| subpapillary layer | The vascular layer of the corium. (05 Mar 2000) |
| subserous layer | The layer of connective tissue beneath a serous membrane such as that of the periconeum or pericardium. Synonym: tela subserosa. (05 Mar 2000) |
| superficial gray layer of superior colliculus | See: gray layer of superior colliculus. (05 Mar 2000) |