(lā′ĕr )

A thin sheetlike structure of more or less uniform thickness.
SEE: stratum

ameloblastic layer

SEE: Enamel layer

bacillary layer

The rod and cone layer of the retina.

basal layer

The outermost layer of the uterine endometrium lying next to the myometrium.
SYN: SEE: basilar layer

basilar layer

SEE: Basal layer.

Bernard glandular layer

SEE: Bernard glandular layer

choriocapillary layer

SEE: Lamina choriocapillaris.

claustral layer

The layer of gray matter between the external capsule and insula.

clear layer

The stratum lucidum of the epidermis.
SEE: stratum lucidum

columnar layer

A layer of tall, narrow epithelial cells forming a covering or lining.

compact layer

The dense surface layer of the uterine endometrium.

cuticular layer of epithelium

A layer of dense cytoplasm at the luminal end of some epithelial cells, esp. the layer at the surface of columnar epithelium of the intestine.

enamel layer

The innermost layer the enamel organ.
SYN: SEE: ameloblastic layer
SEE: enamel organ

ependymal layer

The inner layer of cells of the embryonic neural tube.

epitrichial layer

SEE: Epitrichium.

feeder layer

A layer of connective tissue cells that are used to nourish cultured tissue cells in the laboratory. The feeder cell layer is often derived from mouse fibroblasts. Feeder cells supply metabolites to the cells they support, do not grow or divide, and can be inactivated by gamma irradiation.

functional layer

The portion of the endometrium adjacent to the uterine cavity. After it is shed in menstruation, it is regenerated by the basal layer.
SEE: basal layer

ganglionic layer

1. The fifth layer of the cerebral cortex.
2. The inner layer of ganglion cells in the retina whose axons form the fibers of the optic nerve.

germ layer

Any of the three primary layers of the developing embryo from which the various organ systems develop.
SEE: ectoderm; SEE: endoderm; SEE: mesoderm

germinative layer

The deepest layer of the epidermis, consisting of a basal layer of keratinocytes.
SYN: SEE: malpighian layer; SEE: stratum germinativum

granular exterior layer

The second layer of the cerebral cortex, consisting of pyramidal cells.

granular interior layer

The fourth layer of the cerebral cortex, consisting principally of closely packed stellate cells.

half-value layer

ABBR: HVL The amount of lead, copper, cement, or other material that would dissipate a beam of radiation by 50%. The number of half-value layers required for safety in blocking the area on a patient is five, because that represents 50% of 50% and 50% of that, and so forth. For example, 50% + 25% + 12.5% + 6.23% + 3.12% = 96.9%. Thus the patient would be shielded from all but about 3% of the radiation. (Examples of the thickness of material required to protect from radiation are 2 in [5 cm] of lead or 2 ft [61 cm] of cement.)

Henle layer

SEE: Henle, Friedrich G. J.

horny layer

SEE: Stratum corneum.

Huxley layer

SEE: Huxley, Thomas H.

Langhans layer

SEE: Langhans layer

malpighian layer

SEE: Germinative layer.

mantle layer

The middle layer of the neural tube of the developing embryo.

molecular layer

1. The outermost layer of the cerebral or cerebellar cortex.
2. The inner or outer plexiform layer of the retina.

molecular layer of the cerebral cortex

The most superficial layer of the cortex of the brain, consisting of outer stellate cells and granule cells.

mucus layer

A thick, slippery coating of glycoproteins and other secreted organic chemicals that line and protect the intestinal epithelium.
SYN: SEE: mucus barrier

nervous layer

The portion of the retina that contains the nerves

odontoblastic layer

The layer of connective tissue cells at the outer edge of the pulp where the cells produce the dentin of the tooth.

Ollier layer

SEE: Ollier, Louis Xavier Edouard

osteogenic layer

The inner layer of the periosteum. It contains osteoblasts that become active during repair of fractures.
SYN: SEE: Ollier layer

outer nuclear layer

The layer of the retina containing the nuclei of the visual receptor cells, the rods, and cones.

papillary layer

The superficial layer of the dermis lying immediately under the epidermis into which it extends, forming dermal papillae.
SYN: SEE: stratum papillare

pigment layer

The outermost layer of the retina. Cells contain the pigment fuscin.
SEE: fuscin; SEE: layer of rods and cones

prickle cell layer

SEE: Spinous layer

Purkinje layer

SEE: Purkinje layer

reticular layer

The inner layer of the dermis lying beneath the papillary layer.

layer of rods and cones

The layer of the retina of the eye next to the pigment layer. It contains the rods and cones.
SEE: pigment layer

somatic layer

In the embryo, a layer of extraembryonic mesoderm that forms a part of the somatopleure.
SEE: somatopleure

spinous layer

The layer between the granular and basal layers of the skin. Prickle cells are present in this layer.
SYN: SEE: prickle cell layer; SEE: stratum spinosum
SEE: stratum malpighii

splanchnic layer

In the embryo, a layer of extraembryonic mesoderm that with the endoderm forms the splanchnopleure.

spongy layer

The middle layer of the uterine endometrium, containing dilated portions of uterine glands.
SYN: SEE: stratum spongiosum

subendocardial layer

The layer of loose connective tissue between the endocardium and the myocardium.

subendothelial layer

The layer of fine fibers and fibroblasts lying immediately under the endothelium of the tunica intima of larger arteries and veins.

subodontoblastic layer

A relatively cell-free zone just below the odontoblastic layer in the dental pulp.
SYN: SEE: Weil basal layer

Tomes granular layer

The layer of interglobular dentin beneath the dentinocemental junction in the root of a tooth.

Weil basal layer

SEE: Subodontoblastic layer.

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