This presentation includes histopathology of layers of skin, cells and glands.

1. Basics of Histopathology Of Skin

2. Dermis
Subcutis
Epidermis

3. Epidermis
• Most superficial layer of the skin
• Composed of multiple layers of keratin
containing epithelial cells = keratinocytes with
Melanocytes, merkel cells, and Langerhans
dispersed throughout
• Major functions:
– Maintenance of fluid and electrolyte balance
– Protection from ultraviolet light
– Sensory and immune function

4. Epidermis : Layers
Stratum
Corneum
Stratum Granulosum
Stratum Spinosum
Stratum Basale
Stratum Lucidum
Thin Skin Thick Skin
Rete ridge

5. Differences between thin & thick skin
Thin Skin
• Palms of hands and soles of
feet = acral skin
• 5 layers thick stratum
corneum with increased
granular layer
• More sensory receptors
• Lack sebaceous glands and
increased eccrine glands
• No hair follicles
Thick Skin
• Entire body except thick
skin areas.
• Less than 5 layers of
stratum corneum with no
stratum lucidum
• Hair follicles present except
lips, labia minora, and glans
penis

6. Epidermis
Desmosome = Intercellular Bridges

7. Epidermis: Melanocytes
Melanocytes: clearish
cells in basal layer
with dark nuclei ; ratio
of 1: 10.
Langerhans’s Cells: dendritic cells of the epidermis. Sit in the mid-spinous. Not
visible by light microscopy.

8. Dermal-Epidermal Junction
• Connects the epidermis and dermis
• It is composed of proteins which provide a
firm connection
– Hemidesmosome: connects basal keratinocytes to
basement membrane
– Basement membrane
• Lamina lucida = collagen types XVII, XIII, laminin 5 & 6
• Lamina densa = collagen type VII
– Anchoring fibrils attach the basement membrane
to the dermis hooking on to collagen VII and
collagen I.

9. Basement Membrane
Lamina Lucida
Lamina Densa
Basal layer keratinocytes
of epidermis
Basement Membrane
Hemidesmosomes
Collagen type XVII, XIII
Laminins 5 & 6
Collagen Type VII
Anchoring Fibrils
Dermis
Collagen type I

10. Dermis
• Everything below the dermal epidermal junction /
basement membrane
– Connective tissue layer with contains blood vessels,
nerves, sensory receptors, adnexal structures
- Two layers
• Papillary dermis = includes the dermal papilla which project
into the epidermis
-Capillaries, free nerve endings and encapsulated sensory receptors
called Meissner’s corpuscles.
• Reticular dermis = area between the papillary dermis and
subcutis

11. Papillary Dermis
Papillary
Dermis
Capillaries

12. Reticular
Dermis
Sebaceous
Glands
Erector Pili
muscle
Hair Follicle

13. Dermal Appendages
Hair Follicle
Pilar Muscle
Sebaceous
Glands
Eccrine Glands

14. Sebaceous Glands
• Usually associated with
hair follicles
• Simple branched acinar
glands
– Several acini that empty
into single duct
• Holocrine secretion
• Empty “sebum” into hair
follicle

15. Hair Follicle
Outer Root Sheath
Inner Root Sheath
Hair Cuticle
Hair Medulla
Hair Cortex
cross section
(above the level of the bulb)
Papilla
Bulb
Matrix
Connective Tissue Sheath

16. Eccrine Glands
• Merocrine sweat glands
• Release to adjust body
temperature
• Three cell types
– Dark cells: pyramid shaped
with secretory granules line
lumen of tubule
– Clear cells: located toward
basement membrane
– Myoepithelial cells: spindle
shaped contractile cells

17. Apocrine Glands
• Apocrine glands
– Similar to eccrine glands but
larger lumens and ducts empty
onto superficial regions of hair
follicle
– Release product by shedding of
part of cytoplasm = apocrine
snouting
– Influenced by hormones (sexual
scent glands)
– Only found on axilla, areola,
perianal and genital area

18. Subcutis
Pacinian Corpuscle
• Subcutis
– Area deep to the
dermis
– Includes the
hypodermis
• Loose connective tissue
containing adipose
tissue, nerves, sensory
receptors, arteries and
veins
• Provides a flexible
attachment to the
underlying muscle and
fascia
Hair bulb in the subcutis of
the scalp.
Adipocytes

19. Mucosal epithelium:-
• 2 layers-
1. Surface-stratified
squamous epithelium-
2. Deeper-lamina propria-
fibrous connective tissue-
type I and lll collagen &
elastin fibres.
 Stratified squamous
epithelium:-
1. keratinized-masticatory
mucosa- dorsum of
toungue, hard palate &
attached gingiva.
2. Nonkeratinized- lining
mucosa-buccal,
labial,alveolar mucosa.

20. Regional variation of the skin:-
• Palms and soles - thickened & compact stratum
corneum with stratum lucidum, numerous eccrine
glands & no pilosebaceous units.
• Trunk – significantly thicker reticular dermis.
• Scalp – numerous terminal hair follicles, with most
bulbs in the subcutis.
• Face- prominent sebaceous glands in vellus hairs.

21. • Eyelid- epidermis is thin (2-3 layers thick).
• Modified apocrine glands (Moll’s gland) & vellus hairs
are seen in the dermis.
• Smooth muscle fibres – numerous in dermis of areola,
nipple, also seen in dartos layer in foreskin & scrotum.
• Skin biopsy from legs (adults)- prominent thick walled
blood vessels –gravity and stasis.

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