Skin nontumor
Normal epidermis

Topic Completed: 1 August 2010

Minor changes: 7 April 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Normal epidermis [title]

Mowafak Hamodat, M.B.Ch.B., M.Sc.
Page views in 2019: 2,690
Page views in 2020 to date: 1,052
Cite this page: Hamodat M. Normal epidermis. website. Accessed May 30th, 2020.
Definition / general
  • Epidermis is outer layer of skin
  • Inner layers are dermis and subcutaneous tissue
  • Superficial fascia marks deep boundary between skin and underlying soft tissue
  • Epidermis forms outer layer of keratin that is protective and waterproof
  • Cells present include melanocytes, keratinocytes, Langerhans’ cells and Merkel cells
  • Skin is thicker in palms and soles, which contain epidermal ridges that prevent slipping and form fingerprints and footprints
  • Epidermis is composed of stratified squamous epithelium containing keratinocytes in 4 layers: inner basal, squamous, granular and outer cornified
  • Keratinization takes 30 - 45 days; alterations in pattern and speed cause dermatoses, hyperkeratosis or parakeratosis
Diagrams / tables

Images hosted on other servers:


Microscopic (histologic) description
  • Basal layer:
    • Mitotically active, produces other keratinocytes
    • Contains low molecular weight keratin
    • Separated from dermis by continuous basal membrane; keratinocytes are attached to this membrane by hemidesmosomes
    • Also contains melanocytes

  • Squamous layer (stratum spinosum):
    • Also called prickle or malpighian layer
    • Has several layers of cells, larger than basal layer, which become flat and eosinophilic as they approach the surface due to an increase in keratin and reduction in ribosomes
    • May have clear vacuolated cytoplasm
    • Cells are attached to each other by fine spiny bridges with central dot-like desmosomes (Bizzozero’s nodule)
    • Loss of spiny bridges causes acantholysis

  • Granular layer (stratum granulosum):
    • 1 - 3 layers of flattened cells with intensely basophilic keratohyaline granules, which contain precursors of filaggrin protein, which causes aggregation of keratin filaments

  • Stratum lucidum:
    • Present only in soles and palms, between granular and cornified layer
    • Homogenous eosinophilic zone

  • Cornified layer (stratum corneum):
    • Also called horny layer
    • Basket weave pattern of multiple layers of polyhedral cells without nuclei
    • Region is thicker and more compact in acral region (peripheral body-limbs, fingers, ears)

  • Rete ridges:
    • Undulating forms of epidermis and dermal papillae at dermoepidermal junction - flattens with aging
Microscopic (histologic) images

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Minimal and intense melanin pigment within basal cells

Intraepithelial sweat gland

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