• Stratum corneum: outer layer of the epidermis
  • Consists of dead (anuclear), keratin-filled cells
  • This layer is constantly being sloughed off.
• Stratum lucidum: thin, translucent layer
  • Located only on thick skin (palms and soles)
  • Composed of a homogeneous layer of keratinocytes with no nuclei or organelles
• Stratum granulosum: also called the granular layer
  • Contains keratohyalin
  • This layer has waterproof properties.
• Stratum spinosum
  • Composed of actively dividing keratinocytes with spinous-like projections (prickle cells)
  • This layer produces keratin and induces keratinization.
  • Langerhans cells are also located in this layer.
  • If undergoes malignant changes, will lead to cSCC
• Stratum basale (also called the basal cell layer of the epidermis)
  • Stem cells of the epidermis (their daughter cells migrate upwards and differentiate into other cells)
  • Melanocytes and Merkel cells are also located in this layer.
  • The stratum basale is regenerative (basal keratinocytes proliferate to fill skin defects).

Dermatopathology