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layer

 [la´er]
a thin, flat plate or stratum of a composite structure; called also lamina.
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.
bacillary layer layer of rods and cones.
basal layer of endometrium the deepest layer of the uterine endometrium; it provides the regenerative endometrium after menstrual loss of the functional layer.
basal layer of epidermis stratum basale.
blastodermic layer germ layer.
clear layer stratum lucidum.
columnar layer mantle 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.
germinative layer stratum germinativum.
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.
malpighian layer stratum germinativum.
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.
prickle-cell layer stratum spinosum.
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.
spinous layer stratum spinosum.
spongy layer of endometrium a sublayer of the functional layer of endometrium, underlying the compact layer and containing the tortuous portions of the uterine glands.
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.

lay·er

(lā'ĕr), [TA]
A sheet of one substance's lying on another and distinguishable from it by a difference in texture or color or by not being continuous with it.
See also: stratum, lamina.
Synonym(s): panniculus

layer

/lay·er/ (la´er) a stratum or lamina.
bacillary layer  l. of rods and cones.
basal layer  stratum basale.
blastodermic layer  germ l.
layers of cerebral cortex  six anatomical divisions (I–VI) of the cerebral cortex (specifically the neocortex), distinguished according to the types of cells and fibers they contain.
clear layer  stratum lucidum.
columnar layer  mantle l.
compact layer of endometrium  stratum compactum.
enamel layer  either of two walls, the inner concave wall or the outer convex wall, of the enamel organ.
functional layer of endometrium  stratum functionale.
ganglionic layer of cerebellum  Purkinje l.
germ layer  any of the three primary layers of cells of the embryo (ectoderm, endoderm, and mesoderm), from which the tissues and organs develop.
germinative layer  stratum germinativum.
granular layer 
2. the deep layer of the cortex of the cerebellum.
Henle's layer  the outermost layer of the inner root sheath of the hair follicle.
horny layer  stratum corneum.
malpighian layer  stratum germinativum.
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.
odontoblastic layer  the epithelioid layer of odontoblasts in contact with the dentin of teeth.
prickle cell layer  stratum spinosum.
Purkinje layer , Purkinje cell layer the layer of Purkinje neurons situated between the external molecular layer and the internal granular layer of the cerebellar cortex.
layer of rods and cones  a layer of the retina immediately beneath the pigment epithelium, between it and the external limiting membrane, containing the rods and cones.
spinous layer  stratum spinosum.
spongy layer of endometrium  stratum spongiosum.
subendocardial layer  the layer of loose fibrous tissue uniting the endocardium and myocardium and containing the vessels and nerves of the conducting system of the heart.
subepicardial layer  the layer of loose connective tissue uniting the epicardium and myocardium.

lay·er

(lā'ĕr) [TA]
A sheet of one substance lying on another and distinguished from it by a difference in texture or color or by not being continuous with it.
See also: stratum, lamina

layer

tissue sheet of uniform thickness

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.

lay·er

(lā'ĕr) [TA]
A sheet of one substance's lying on another and distinguishable from it by a difference in texture or color or by not being continuous with it.
See also: stratum, lamina

layer

1. stratum; a sheetlike mass of tissue of nearly uniform thickness, several of which may be superimposed, one above the other, as in the epidermis.
2. a commercial fowl which is laying eggs, i.e. a female of more than about 5 months of age, up to the stage of being a 'spent hen' suitable only for slaughter.

basal layer
1. the deepest layer of the epidermis. See also stratum basale.
2. the deepest layer of the uterine mucosa.
blastodermic layer
germ layer (see below).
clear layer
stratum lucidum; the clear translucent layer of the epidermis, just beneath the horny layer.
columnar layer
1. layer of rods and cones.
2. mantle layer.
compact layer
the layer of the endometrium nearest the surface, containing the necks of the uterine glands.
functional layer
the compact and spongy layers of the endometrium considered together.
cerebellar ganglionic layer
the thin middle gray layer of the cortex of the cerebellum, consisting of a single layer of Purkinje cells.
germ 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.
germinative layer
any proliferative layer such as the basal layer of the epidermis or the lower layer of the claw, from which the claw grows.
granular layer
1. the layer of epidermis between the clear and prickle-cell layers; called also stratum granulosum.
2. the deep layer of the cortex of the cerebellum.
3. the layer of follicle cells lining the theca of the vesicular ovarian follicle.
horny layer
1. stratum corneum; the outermost layer of the epidermis, consisting of dead and desquamating cells.
2. the outer, compact layer of the claw, etc.
keratohyaline layer
granular layer (1).
mantle layer
the middle layer of the wall of the primitive neural tube, containing primitive 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.
prickle-cell layer
stratum spinosum; the layer of the epidermis between the granular and basal layers, marked by the presence of prickle cells.
layer of rods and cones
a layer of the retina immediately beneath the pigment epithelium, between it and the external limiting membrane, containing the rods and cones.
spinous layer
prickle-cell layer.
spongy layer
the middle layer of the endometrium, containing the tortuous portions of the uterine glands.
subendocardial layer
the layer of loose fibrous tissue uniting the endocardium and myocardium.
zonal layer of thalamus
a layer of myelinated fibers covering the dorsal surface of the thalamus.