Understanding the Epidermis: Structure, Function, and Layers

Epidermis

- Outermost layer of the skin

- Composed of stratified squamous epithelium

- 4-5 cell layers thick (thin), 100-120 µm in thickness

- Derived from ectoderm

- Avascular (no blood vessels)

- Cells synthesise keratin as they undergo apoptosis (programmed cell death)

- Outermost cells become dehydrated and form corneocytes, which are composed primarily of keratin and are sloughed off by friction

- Keratinocytes: the most common cell type (90%)

- Melanocytes: 8%

- Langerhans cells: part of the immune system (2%)

- Merkel cells: sensory receptors (0.5%)