| vascular layer of choroid coat of eye | <anatomy> The outer portion of the choroid of the eye containing the largest blood vessels. Synonym: lamina vasculosa choroideae, Haller's vascular tissue, uvaeformis, vascular layer of choroid coat of eye, vascular layer. (05 Mar 2000) |
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| malpighian layer | The living layer of the epidermis comprising the stratum basale, stratum spinosum, and stratum granulosum. Synonym: malpighian layer, malpighian rete. (05 Mar 2000) |
| papillary layer | The more superficial layer of the corium whose papillae interdigitate with the epidermis. Synonym: corpus papillare, papillary layer. (05 Mar 2000) |
| Rauber's layer | The thinned-out trophoblastic membrane over the embryonic disk in developing carnivores and ungulates, outermost cell layer which helps form the blastodisk; called blastodermic or primitive ectoderm. (05 Mar 2000) |
| mantle layer | The nuclear zone of the developing neural tube between the marginal layer and the ependymal layer; forms the gray matter of the central nervous system. Synonym: intermediate layer, mantle zone. (05 Mar 2000) |
| ventricular 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) |
| marginal layer | The outer, nonnuclear layer of the embryonic neural tube; into its fibrous network grow the longitudinal nerve fibres which eventually become the white matter of the cord and brain stem. Synonym: marginal zone. (05 Mar 2000) |
| germinative layer | The deepest layer of the epidermis, composed of dividing stem cells and anchoring cells. Synonym: basal cell layer, columnar layer, germinative layer, palisade layer, stratum basale, stratum cylindricum, stratum germinativum. (05 Mar 2000) |
| germinative layer of nail | The deeper layer of the nail that is continuous with the stratum germinativum of the surrounding skin and from which the nail plate is continuously formed. Synonym: germinative layer of nail. (05 Mar 2000) |
| germ layer | <embryology> A layer of cells produced during the process of gastrulation during the early development of the animal embryo, which is distinct from other such layers of cells, as an early step of cell differentiation. The three types of germ layers are the endoderm, ectoderm, and mesoderm. Diploblastic organisms (e.g. Coelenterates) have two layers, ectoderm and endoderm, triploblastic organisms (all higher animal groups) have mesoderm between these two layers. Germ layers become distinguishable during late blastula/early gastrula stages of embryogenesis and each gives rise to a characteristic set of tissues, the ectoderm to external epithelia and to the nervous system for example: although some tissues contain elements derived from two layers. (18 Nov 1997) |
| germ layer theory | The developmental biology theory that during early development, the animal embryo divides itself into two or three germ layers, each of which then proceed to further differentiate into organs and tissues specific to that particular layer. (09 Oct 1997) |
| glomerular layer of olfactory bulb | A layer composed of spherical bodies, called glomeruli, formed by the synapses of mitral cells with the olfactory nerve fibres derived from the cells of the olfactory epithelium. (05 Mar 2000) |
| visceral layer | The inner layer of an enveloping sac or bursa which lines the outer surface of the enveloped structure, as opposed to the parietal layer which lines the walls of the occupied space or cavity. The visceral layer is usually thin, delicate and not apparent as being separate, but rather appears to be the outer surface of the structure itself. Synonym: lamina visceralis. (05 Mar 2000) |
| visceral layer of tunica vaginalis of testis | The inner part of the tunica vaginalis testis applied directly to the testis and epididymis. Synonym: lamina visceralis tunicae vaginalis testis. (05 Mar 2000) |
| medial cartilaginous layer | The broad medial portion of the cartilaginous part of the auditory tube. Synonym: lamina medialis cartilaginis tubae auditivae, lamina cartilaginis medialis tubae auditivae, medial cartilaginous layer, medial layer of cartilaginous auditory tube. (05 Mar 2000) |