Stratum corneum = horny layer
consists of flat cells melted together and containing keratin, those
cells are without
cell organelles.
The cells of the uppermost layer (Stratum disjunctum) are separated as
epidermal scales (squama cornea).
Stratum lucidum
is a layer which refracts the light rays very strongly = a clear layer,
it contains proteoglycans
(macromolecular glycoproteins) and lipids (fat).
Stratum granulosum
is the layer where the cells start to become horny (epitheliolysis).
It is also called granulosa layer of Langerhans.
Stratum spinosum = prickle cell layer
is multi-layered and consists of polygon-shaped cells joined together
by desmosomes (visible in the electron microscope as thickening of the
cell membrane).
In this layer the keratinocytes are joined by tonofibrils (a filament
of proteins) like a network. In addition the melanocytes are located
in this layer, which produce the pigment melanin. This pigment works
as protection against UV-rays.
Keratinocytes = cells of the skin producing keratin; so called
prickle or MALPIGHIAN cells.
Stratum basale = basal layer
is, together with the stratum spinosum, responsible for cell
reproduction in this layer; this layer consists of tall cylindrical cells
(Epitheliocytus basalis) and melanocytes.
Here the cell division occurs and new prickle, granular and lucidal
cells are produced.
Stratum papillare = papillary layer
Is a loose connective tissue extending with plug-like projections to
the basal membrane and the epidermis. These projections are called
papillae which enlarge the contact area between the epidermis and the
dermis and thus improve the nutrition of the epidermis, which does not
have any vessels. The papillae also take part in the regulation of the
body temperature. In the region of the papillae lymphatic
vessels, receptors for heat and cold and the sense of touch
start.
Meissner corpuscle (disks) = Corpuscula tactus
are receptors for the tactile sensation.
Follicle
are bubble-like structures, for example hair-follicle, dental follicle
(dental sac), ovarian follicle.
Ruffini's corpuscle (expansion receptor)
are coiled tube-like nerve ending corpuscles located in the corium and
subcutis; they transfer the feeling for heat.
Stratum reticulare = reticular layer
consists of collagenous fibers which weave throughout it and cross
each other in very distinct angles. By changing the degree of their
angle the skin can be stretched without changing its
resistance to tearing.
Collagenous fiber = connective tissue fiber,
consisting of proline-rich scleroprotein (Proline = an amino-acid,
called pyrrolidine-2-carbon acid).
Sebaceous gland = Glandula sebacea
produces the so called sebaceous matter.
The sebaceous matter (Latin: sebum) keeps hairs and the upper layer of
the skin, the horny layer (stratum corneum) elastic.
Sweat gland = Glandula cutis
These glands are responsible for the thermoregulation of each organism
by using the physical effect of evaporation. The sweat keeps the skin
elastic and ensures a correct pH value.
For example: eccrine sweat glands, apocrine sweat glands, sebaceous
glands, ciliary glands, mammary glands.
Adipose fat = fat pad
works like pillows ("shock absorbers"), protects against
cold and is an energy deposit.
The carbohydrates included in food are stored as fat.
Adipose = fatty
Vater-Pacini's corpuscle = Corpuscula lamellosa
are a type of nerve ending corpuscles, which can be found for example
in the skin, in connective tissues, in the mucous membrane of inner
organs, in the heart, in the peritoneum, and near vessels.
They work as vibration and acceleration detectors.
Function of the skin
The skin
