CosBeauty Magazine #98

EPIDERMIS
The epidermis is the outer-most layer of the
skin and continually renews and regenerates.
Ultimately, all the cells in the epidermis
originate from a single layer of basal cells
in its basement membrane – these are
called keratinocytes, which are stacked on
top of each other to form several strata,
melanocytes and dendritic cells.
Keratinocytes develop in the basal layer
and rise, losing their central nucleus and
producing skin proteins called keratins and
fats called lipids, before being shed from
the surface of the skin as dead cells. As they
move towards the surface of the skin, their
form changes and they create distinct layers
known – from the bottom up – as the basal
layer, the spiny layer, granular layer, stratum
and stratum corneum.
In the spiny layer, the keratinocytes make
lipid fat cells which discharge as the cells
move up through the granular layer, forming
a moisture-carrying mortar around the basal
cells, which are now called corneocytes.
These effectively dead and flattened cells
form the protective outer layer of skin,
which is worn away in a process known as
desquamation. The entire process normally
takes around 30 days – although sunburn,
injury or cosmetically stripping the outer
layer speeds the process.
The stratum corneum retains moisture in
the lower skin layers, comprising up to 15
percent water. Moisture loss is regulated by
the lipids, while dead cells are cleared away
by skin enzymes.
Men tend to have a thicker stratum
corneum than women; they tend to have
more collagen and produce more sebum,
making the lipid layer of their skin thicker
and the cell renewal process slower.
Melanocytes produce melanin, which
contributes to skin colour and provides UV
protection. Dendritic (or Langerhans) cells
are involved in the immune system of the
skin. They consume foreign materials that
invade the epidermis and transfer out of the
skin to stimulate an immune response.
DERMIS
Between the epidermis and the
subcutaneous fat layer lies the dermis,
which contains connective tissue and houses
the arteries, hair follicles, lymph vessels,
sensation receptors, sweat glands and
veins. This thicker dermal layer is composed
primarily of collagen, which is responsible
for the strength and elasticity of the skin. It is
held together by a protein called elastin that
is produced by fibroblast cells. The dermis
also contains moisture-storing glycoproteins
and hyaluronic acid, which have the ability
to attract and bind hundreds of times its
weight in water. Here, collagen and elastin
production decline with ageing.
HYPODERMIS
The hypodermis, also referred to as the
subcutis, subcutaneous layer or superficial
fascia, is the bottommost layer. As the
deepest component of skin, the hypodermis
is made up of a loose network of fat and
collagen cells. It acts as a protective cushion
and helps insulate the body by monitoring
heat gain and heat loss. The thickness of this
layer can vary significantly in individuals and
in different parts of the body. CBM
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