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Chapter 5Skin Histology
Epidermal Derivatives
J.F. Thompson, Ph.D.
Hair Distribution Varies Over the
Body Surface
Hair Follicles
Hair Anatomy• Shaft
– medulla - inner layer– cortex - middle layer, pigments, air spaces– cuticle - outermost layer, hard keratin
• Root– similar to shaft, but within dermis
• Follicle - surrounds root
• Sheath - supports shaft & root
• Bulb - enlarged layered structure at base where hair is generated– papilla - areolar connective tissue, blood
vessels supply nutrients– matrix - germination layer of papilla
(stratum basale) builds hair shaft
• Sebaceous glands – release oil
• Arrector Pili – smooth muscle
Hairs & Lice
egg
headlouse
crab louse
Arrector Pili (smooth muscle)
Sweat Glands
Sebaceous Glands
Nails• tightly packed, hard,
keratinized cells• nail matrix - under root
of nail– site of nail growth– transforms normal skin
cells into nail cells which push forward
– 1mm/week in fingers; slower in toes
– the longer the finger the greater the growth rate
Nails• Tightly packed cells with
hard keratin
• Nail matrix - under root of nail– site of nail growth– transforms normal skin
cells into nail cells which push forward
– 1mm/week in fingers; slower in toes
– the longer the finger the greater the growth rate
Hypodermis
End Ch 5
Skin HistologyEpidermal Derivatives