Recall names of the 3 layers of the skin
Identify the layers of the Epidermis
List the difference with the dermis &
Label the appendages of the skin
The skin is made up of 3 main layers:
This is the outermost layer of the skin (the part that you can see); it does not
have a blood supply of its own and is made up of 5 layers:
The Keratinisation Zone
The skin cells begin to die in these layers. The cells become flatter, and harden.
The Germinative Zone
All these cells in the epidermis are living.
The stratum corneum
This is the surface layer of skin, consisting of 25 to 30 cells deep of flattened
irregular dead keratinised cells. This layer of skin is a waterproof protective
covering, which prevents excessive dehydration of the tissues, hence the
term horny layer.
The stratum lucidum
This layer lies below the stratum corneum and is four cells deep and a
narrow transparent layer consisting of flattened and closely packed cells, with
an indistinct outline and no nuclei hence the term clear layer. This layer is
more pronounced in thick hairless skin, eg on the palms of the hands and
soles of the feet.
The stratum granulosum
This is the third layer of the epidermis and is between one and three cells
deep, consisting of flattened spindle shaped cells. The nucleus begins to
breakdown here and granules of keratin appear, hence the term granular
layer. This layer forms the main part of all horny tissue.
The stratum spinosum/prickle cell layer
This layer is eight cells deep with round nucleated cells, which vary in size
and shape and produce fibrils which interconnect them with neighbouring
cells, hence often referred to as the prickle cell layer.
The stratum germinativum/basal layer
Within this layer cells are one cell deep, rounded and clearly defined with a
nucleus, and rest on the papillae of the dermis. These epithelial cells are
able to divide and reproduce themselves by a process called mitosis, hence
the term germinative. As these cells form they push themselves up towards
the skin surface. Within this layer there are also melanocyte cells, which
produce the pigment melanin, which gives both the hair and skin its colour
density. Langerhan cells are also found within this layer and absorb and
remove foreign bodies that enter the skin.
This layer is often referred to as the true skin as it forms the bulk of the
skin. It is composed of connective tissue, and is thicker than the epidermis.
The dermis contains 2 layers:
This lies directly under the epidermis, it is quite thin and has cone. These
contain nerve endings and blood capillaries.
It provides nutrients and oxygen to the germinating layer of the epidermis
This lies below the papillary layer and is the main portion of the dermis.
Within the reticular layer are collagen
and elastin fibres.
Read the description of dermis, and highlight key words on the