layer
[la´er] ameloblastic layer the inner layer of cells of the enamel organ, which forms the enamel prisms of the teeth.
abrasion layer a protective covering of gelatin enclosing an emulsion on x-ray film; called also
overcoat.
basal layer of endometrium the deepest layer of the uterine
endometrium; it provides the regenerative endometrium after menstrual loss of the
functional layer.
compact layer of endometrium a sublayer of the
functional layer of endometrium, which faces the lumen of the uterus and contains the necks of the
uterine glands.
enamel layer the outermost layer of cells of the enamel organ.
functional layer of endometrium the layer of
endometrium facing the lumen of the uterus; its cells are cast off at menstruation and childbirth. Sublayers are the
compact layer and the
spongy layer. It is known as the
decidua during pregnancy.
ganglionic layer of cerebellum the thin middle gray layer of the cortex of the cerebellum, consisting of a single layer of Purkinje cells.
germ layer (
germ cell layer) any of the three primary layers of cells formed in the early development of the embryo (
ectoderm,
entoderm, and
mesoderm), from which the organs and tissues develop.
granular layer 2. the deep layer of the cortex of the cerebellum.
3. the layer of follicle cells lining the theca of the vesicular ovarian follicle.
half-value layer the thickness of a given substance which, when introduced in the path of a given beam of rays, will reduce its intensity by one half.
Henle's layer the outermost layer of the inner root sheath of the hair follicle.
horny layer 2. the outer, compact layer of the nail.
mantle layer the middle layer of the wall of the primordial neural tube, containing primordial nerve cells and later forming the gray matter of the central nervous system.
nervous layer all of the retina except the pigment layer; the inner layer of the optic cup.
odontoblastic layer the epithelioid layer of odontoblasts in contact with the dentin of teeth.
Ollier's layer the innermost layer of the periosteum.
layer of rods and cones the layer of the nervous part of the
retina, located between the pigmented part and the external limiting membrane, containing the sensory elements, the
rods and
cones.
subendocardial layer the layer of loose fibrous tissue uniting the endocardium and myocardium.
subepicardial layer the layer of loose connective tissue uniting the epicardium and myocardium.
zonal layer of thalamus a layer of myelinated fibers covering the dorsal surface of the thalamus.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
layer
A sheet of one thickness lying over or under another and distinguished from it by a difference in composition or colour.
Bowman's layer Thin layer of the cornea (about 12 μm) located between the anterior stratified epithelium and the stroma. This layer is acellular; it is a modified superficial stromal layer found only in primates. It is composed of a randomly orientated array of fine collagen fibrils, primarily of collagen types I, III and V.
Syn. anterior limiting layer; Bowman's membrane; lamina elastic anterior.
layer of Chievitz, transient A temporary layer found in the developing embryonic retina lying between the inner neuroblastic layer (which will form the ganglion, amacrine and Mueller cells) and the outer neuroblastic layer (which will form the bipolar, horizontal and photoreceptor cells). It contains the inner processes of Mueller's fibres.
Haller's layer An outer layer of the choroid lying between Sattler's layer and the suprachoroid. It contains connective tissue and large vessels, mainly veins.
layer of Henle, fibre Located in the macular region, it is formed by the cone and rod fibres that run parallel to the retinal surface within the outer molecular layer of the retina.
See Haidinger's brushes;
macular star.
retinal layer's See retina.
Sattler's layer An inner layer of the choroid lying between the choriocapillaris and Haller's layer. It contains small blood vessels.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann