This document provides an overview of human skin histology at the microscopic level. It describes the main tissue layers that make up skin (epidermis, dermis, hypodermis) and common cell and structure types found within each layer. Key structures highlighted include hair follicles, sebaceous glands, sweat glands, blood vessels, nerves, and specialized sensory receptors like Meissner's and Pacinian corpuscles. Comparisons are made between thin and thick skin types, as well as different hair follicle and gland morphologies. The purpose is to serve as a guide for identifying and interpreting features seen under the microscope in skin histology slides.

1. SKIN HISTOLOGY:
UP CLOSE AND PERSONAL
A Laboratory Guide

2. SLIDES TO CONQUER
• 56a: Thin skin, H & E
• 56b: Thick skin, Masson, H & E
• 56e: Scalp
• 56f: Pacinian corpuscle
• 56g: Meissner corpuscle

3. KNOW THE HIERARCHY OF
HISTOLOGIC ORGANIZATION
CELLS (Keratinocytes, etc.)
+ ECM
TISSUE
Epithelial tissue (= EPIDERMIS)
Connective tissue (=DERMIS/HYPODERMIS)
Nervous tissue
Muscle tissue
Blood tissue
ORGAN
Skin

4. SKIN (Organ)
EPITHELIAL
TISSUE NERVOUS
(=Epidermis, CONNECTIVE BLOOD MUSCLE
TISSUE TISSUE
glands, TISSUE TISSUE
endothelium (=Dermis, (=Free nerve
hypodermis) (=Smooth
of blood endings,
muscle cells in
vessels) encapsulated
blood vessel
receptors,
wall, platysma,
Merkel cell)
Arrector pili)

5. • EPITHELIAL TISSUE • CONNECTIVE TISSUE
– CELLS CLOSELY – CELLS FEW AND FAR
PACKED TOGETHER BETWEEN
W/ INTERCELLULAR – ABUNDANT
JUNCTIONS EXTRACELLULAR
– SCANTY MATRIX
EXTRACELLULAR • FIBERS
MATRIX • GROUND SUBSTANCE
– AVASCULAR – VASCULAR
– GLANDS
*INTIMATE RELATIONSHIP - ATTACHED TOGETHER BY
A BASEMENT MEMBRANE

6. ORIENT THE SLIDE PROPERLY!
X

7. RECOGNIZE THE TISSUE • EPIDERMIS
– Stratified squamous
COMPONENTS THAT keratinized epithelium
– Superficial
MAKE UP THE SKIN – Thinner
• DERMIS
– Dense irregular
connective tissue
– Thicker
• EPIDERMAL-DERMAL
INTERFACE
– Wavy
– Basement membrane not
visible w/ H & E
• HYPODERMIS
– Loose connective tissue
– May have abundant
adipose cells

8. IDENTIFY THE
LAYERS
• EPIDERMIS
– More deeply staining
– Highly cellular (multiple
layers)
• DERMIS
– Paler
– Mostly Fibers (irregular
bundles) and some
ground substance
(poorly stained w/ H &
E)

9. ARTEFACT!
• ISLANDS OF
DERMAL
PAPILLA
WITHIN THE
EPIDERMIS
(due to
tangential
sectioning)

10. THIN SKIN VS THICK SKIN
Slide 56a Slide 56b

11. LAYERS OF THE
EPIDERMIS
(thick skin)
• S. corneum
• S. granulosum
• S. spinosum
• S. basale

12. • S. corneum
– Anucleate
– flattened layers
– “basketweave”
• S. granulosum
– Diamond shaped
– Darkly staining
cytoplasmic granules
• S. spinosum
– Polygonal
– Rarely see “spines”
• S. basale
– Single layer, cuboidal cells
– Crowded nuclei
– Occ. Mitotic figures

13. MELANOCYTE (thin fair skin)

14. MELANOCYTE (Pigmented skin)

15. LANGERHANS CELL

16. LAYERS OF THE DERMIS
• Papillary dermis
– Contains dermal papilla
– Thin collagen fibers
– More cells (fibroblasts)
– Smaller blood vessels
(capillaries)
• Reticular dermis
– Thick collagen fibers
– Bigger blood vessels
(arterioles/venules)
– *Elastic network NOT
distinguished from collagen
with H&E

17. VELLUS vs TERMINAL
(most of body) (scalp)
• Superficial • Deeper
• Smaller • Bigger
• Lightly pigmented • Darkly pigmented

18. Slide 56e: Scalp
• HAIR FOLLICLES
– Terminal (up to
hypodermis)
– Various planes of
section
– Mostly anagen
– Oblique
– Continuous with
the surface
epidermis

19. ANAGEN HAIR FOLLICLE
• Hair shaft
• Hair bulb
• Hair matrix
• Hair papilla

20. LAYERS OF THE
HAIR FOLLICLE:
Longitudinal section
• Hair shaft
• Inner root sheath
• Outer root sheath
• Fibrous sheath

21. LAYERS OF THE HAIR FOLLICLE:
Cross Section

22. PILOSEBACEOUS
UNIT
(Longitudinal
section)
• Arrector pili muscle
– Attaches to lower
third of HF
• Sebaceous gland
– Duct enters into
upper third of HF

23. PILOSEBACEOUS
UNIT: Cross
section
• Hair Follicle
• Sebaceous gland
lobules

24. SEBACEOUS
GLAND
• CENTRAL: Vacuolated
lipid-filled cells w/
scalloped nuclei
• eventually
disintegrating
together with sebum
into duct
• PERIPHERAL: row of
flattened germinative
cells w/ large nuclei &
basophilic cytoplasm

25. ECCRINE GLAND: LPO
Coiled portion in deep dermis

26. ECCRINE GLAND:
Coiled portion in
deep dermis (HPO)
• SECRETORY PORTION
– Pale
– More cross sectional
profiles, some tangential
and bizarre-shaped
(=tadpole)
• DUCTAL PORTION
– Dark
– Fewer, more regularly
rounded profiles

27. ECCRINE GLAND: Coiled basal
portion
• Secretory portion
– Single layer
– Pale pyramidal cells
• Ductal portion
– 2 layers
– Eosinophilic cuboidal
cells
– Hyaline lumenal lining

28. INTRAEPIDERMAL ECCRINE DUCT
(=Acrosyringium)
• Corkscrew
appearance
• Ductal cells
are also
keratinized

29. MEISSNER PACINIAN
CORPUSCLE (56g) CORPUSCLE (56f)

30. MEISSNER vs. PACINIAN
CORPUSCLE CORPUSCLE

31. BLOOD
VESSELS in
Reticular dermis
• Arterioles
• Venules

32. Capillaries in Dermal papilla
MEISSNER’S CORPUSCLE
LYMPHATIC VESSEL