Epidermis (magnified skin block)
Epidermis
Integumentary (skin)SkinLeg
- What it is
- The outer, cell-only layer of skin: a keratinised stratified squamous epithelium (basal, spinous, granular and horny layers) whose underside interlocks with the dermal papillae in rete ridges. It has no blood vessels.
- Function
- Waterproof, microbe- and UV-resistant barrier; melanocytes add pigment, Langerhans cells police for pathogens, Merkel cells sense light touch.
- Size
- Real thickness ~0.05–0.1 mm (eyelids) to ~1.5 mm (palms, soles); shown magnified ~x20
- Clinical note
- The epidermis renews itself about every 4 weeks: basal cells divide, flatten and die as they rise, and ~500 million dead cells are shed daily.