Taber's Medical Dictionary
layer
(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
choriocapillary layer
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
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
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.
