The Stratum Germinativum/basal 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.

The structure of the dermis

The dermis has two layers: the papillary and reticular layers.

The papillary layer – supplies the blood supply to the epidermis

This lies directly under the germinative layer and nourishes the epidermis. It contains small cone shaped projections called papillae which contain looped blood capillaries. The papillary layer contains nerve endings which register sensations, Mast cells which burst when stimulated during inflammation or allergic reactions and release: Histamine (a hormone released into the skin that causes blood vessels clearly to enlarge as a warning sign)

Macrophages: these destroy microorganisms and engulf dead cells and other unwanted particles. Lymphatic vessels, carrying lymph away from the connective tissues

The reticular layer

This is the larger of the two layers containing cells called fibroblasts, which produce the formulation of elastin and collagen which give the skin its flexibility and ability to recoil. The reticular layer also contains nerve endings which register sensations

The Dermis also contains:

Hairs in hair follicles, Arrector pilli muscle (this contract when we are cold so that our hairs stand up and trap warm air to keep us warm: goosebumps)

Eccrine sweat glands are all over our body and secrete an odourless sweat. Appocrine sweat glands are developed during puberty in our pubic region and underarms. They produce a milky odour sweat. Sweat is produced to help regulate body temperature.

Sebaseaous glands are attached to the hair follicle and secrete sebum. Sebum is combined with sweat on our skin to form the acid mantle.

The dermis has a complex blood and lymph capillary network to bring oxygen and nutrients to the skin and take away toxins.

The subcutaneous layer

This layer contains adipose tissue which is also called fatty or subcutaneous tissue and there are different types of fat cells within this tissue. Adipose cells store fat. Fat cells are made of Areolar connective tissue and are found located in the subcutaneous layer of the skin and around vital organs.

The functions of adipose tissue are:

1. Protection
2. To act as a shock absorber, supporting delicate structures such as blood vessels
3. Stores energy
4. Adipose tissue helps maintain body temperature as it is a heat source