stratum germinativum

stratum

 [stra´tum, strat´um] (L.)

a sheetlike mass of tissue; see also lamina and layer.

stratum basa´le the deepest layer of the epidermis, composed of a single layer of basophilic cells. Called also basal layer of epidermis.

stratum cor´neum the outer horny layer of the epidermis, consisting of cells that are dead and desquamating. Called also horny layer.

stratum germinati´vum

1. the stratum basalis and stratum spinosum considered together; called also malpighian layer.

2. the lower layer of the nail, from which the nail grows; called also germinative layer.

stratum granulo´sum the cell layer of the epidermis lying between the stratum lucidum and the stratum spinosum. Called also granular layer.

1. the deep layer of the cortex of the cerebellum.

2. the layer of follicle cells lining the theca of the vesicular ovarian follicle; called also granular layer.

stratum lu´cidum the clear translucent layer of the epidermis, just beneath the stratum corneum. Called also clear layer.

stratum spino´sum the layer of the epidermis between the stratum granulosum and stratum basalis, marked by the presence of prickle cells; called also spinous layer and prickle-cell layer.

strat·um ba·sa·le ep·i·derm·i·dis

the deepest layer of the epidermis, composed of dividing stem cells and anchoring cells.

Synonym(s): basal cell layer, columnar layer, germinative layer, palisade layer, stratum basale (2) , stratum cylindricum, stratum germinativum

stratum germinativum

See stratum basale.

stratum basale

; stratum germinativum; germinal layer; basal layer deepest layer of the epidermis lying at dermoepidermal junction, keratinocytes and melanosomes Table 1

Table 1: Constituents of skin

Constituent	Components
Epidermis	Stratified squamous epithelium formed from keratinocytes Basal layer: keratinocytes linked by desmosomal and hemidesmosomal and filamentous connections (cytoskeleton; prevents shear) Spinous layer: keratinocytes shrink, retaining contact only at desmosomes and hemidesmosomes Granular layer: keratinocytes secrete complex lipids which act as a semipermeable skin barrier Corneal layer: cell and contents have become keratin to form squames moved towards the exterior
Epidermal cells	Keratinocytes Melanocytes: lie between keratinocytes; secrete pigment and protect keratinocyte nuclei from ultraviolet radiation Merkel cells: sensory cells Langerhans cells: within spinous layer; antigen-presenting cells
Basement membrane zone	Collagen, hemidesmosomes, laminin which aid adhesion of epidermis to dermis; dysfunctional in disease such as epidermolysis bullosa
Dermis	Mesodermal tissue containing blood vessels, nerve, muscle, skin appendages (sweat glands, sebaceous glands, hair follicles), immune cells (histamine-releasing mast cells) in a matrix of collagen, elastin and hyaluronic acid
Subcutaneous layer	Adipose tissue, blood vessels and nerves, acting as an insulating layer

stratum

pl. strata [L.] a sheetlike mass of tissue of fairly uniform thickness; distinct layers making up various tissues or organs, as of the skin, brain, retina.

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stratum avasculosum

the avascular stratum in the margin of the iris.

stratum basale

the mitotically active, basal layer of the epidermis, consisting of columnar to cuboidal keratinocytes on a basement membrane.

stratum corneum

the outer horny layer of the epidermis, consisting of cells that are non-nucleated, keratinized and desquamating.

stratum germinativum

in the epidermis, located between the stratum basale and the stratum granulosum. Together with the basal layer, called the malpighian layer. Called also germinative layer.

stratum granulosum

1. the layer of cells between the stratum lucidum and the stratum spinosum of the skin, very thin and not always present. Called also the 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. Called also granular layer.

stratum lamellatum

laminae of the hoof corium.

stratum lucidum

the translucent layer of the skin just beneath the stratum corneum. Called also clear layer. Present in the epidermis of the planum nasale of several species and footpads of carnivores.

stratum spinosum

the layer of the epidermis between the stratum granulosum and the stratum basale, marked by the presence of prickle cells; called also spinous layer and prickle-cell layer.

stratum tectorium

the layer of horny scales claimed to exist on the surface of the horse's hoof that gives it the smooth glossy appearance.