The SKINThe SKIN

D r . S a m a r A s k e rD r . S a m a r A s k e r

The largest organ in the body

ProtectionRegulation

ExcretionSynthesis

Receive sensation

Medico legal

functions

Diagnose some diseases as : Measles anemia Jaundice chicken pox.

Types of the skin Thick skin Palm, sole, tips of

Fingers& toes

Thin skinAll over the body

Thick skinFormed of

epidermis & dermis.

The epidermis keratiniezed str.sq.epith

formed of. Keratinocytes & non Keratinocytes

The Keratinocytes:85% of cells of epidermis form keratin 5 layers .

1

2

345

•Basal layer together with Spinous layer are called malpighian layer

Basal cell layer or Germinal l. LM: •Single layer of columnar cells resting on clear wavy basement membrane . Have basal oval nucleus & basophilic Cytoplasm. •The nuclei show mitotic figures for renewal which take place every 2-4 weeks mostly at night .

EM: •Cells are joined together by “desmosomes” • to the basement membrane by “hemidesmosomes”. •Rich in ribosomes and polysomes

•Melanocytes •Merkels cells are present in this layer.

Spinous layer or Prickle cell l. LM:

•4-8 layers of polyhedral cells with central and rounded nuclei.•They have spine-like processes indicating sites of desmosomes as cells shrink during preparation.

EM:•The cells are joined by “desmosomes” & have interdegitating cell membrane.•The superficial cells contain membrane bound (coated) lamellar granules.•Langerhans cells are present in this layer