1. Skin Histology Epidermis J.F. Thompson, Ph.D.
Chapter 5
Skin Histology
Epidermis
J.F. Thompson, Ph.D.

2. The Architecture of the Skin
2 Principal portions
Epidermis - epithelium
Dermis – areolar and dense irregular fibrous connective tissue
Hypodermis
“beneath the dermis”
the subcutaneous layer next to:
adipose layer or
muscle or
bone

3. The Epidermis Stratified Squamous Epithelium 4 cell types
Keratinocytes - 90%
filled with keratin (protein)
waterproof barrier
Melanocytes - 8%
produce melanin (pigment)
pass melanin to keratinocytes
Langerhans cells
phagocytes (from immune system)
easily damaged by UV light
Merkel cells
in deepest layer of hairless skin
sensory transduction - touch

4. Keratinocytes and Melanocytes

5. Merkel Cells

6. Langerhans Cells

7. Epidermal Cell Layers Stratum basale Stratum spinosum
A single layer of cuboidal/columnar cells
Stem cells, melanocytes, Merkel cells
Stem cells  keratinocytes, mitosis pushes the other layers to the top
Stratum spinosum
8 to 10 layers of closely packed cells
Cell junctions - spot desmosomes
Langerhan’s cells

8. Epidermal Cell Layers Stratum granulosum Stratum lucidum
3-5 layers of flattened, with keratohyaline granules
beginning breakdown of nucleus, cell death initiated
Stratum lucidum
only in thick skin (palms, feet)
3-5 layers of clear, flat dead cells with keratin
Stratum corneum
20-30 layers of flattened, dead, keratin-filled cells
continuously shed and replaced
2-4 weeks for each cell to form and to move from the stratum basale to the surface

9. Thin Skin

10. Thin Skin Stratum Corneum Stratum Granulosum Stratum Spinosum
Stratum Basale

11. Thick Skin

12. Skin Histology Epidermis
End Ch 5
Skin Histology
Epidermis