MH 086c Scalp

Hair Follicles

Thin skin with cross-sections of hair follicles and their associated sebaceous glands.

• Hair Follicles - hair shafts (which are absent in most follicles) are found at the center of hair follicles. These structures are described from the center outwards.
• • Hair Shaft - cortex and medulla of keratinized cells.
  • Cuticle - squamous cells form the outermost layer of hair.
  • Internal Root Sheath - extends from the hair bulb to the level of sebaceous glands.
    • Huxley's Layer - single or double layer of flattened cells.
    • Henle's Layer - outer single layer of cuboidal cells.
  • External Root Sheath - layers of cells continuous with the epidermis.
  • Glassy membrane - thick basement membrane that separates the hair follicle from the dermis.

• Sebaceous Glands - produce a lipid rich secretion called sebum that is released into the hair follicle.
  • The gland is a cluster of cells with clear cytoplasm because the lipid was extracted during preparation.
  • Large cells with a central nucleus and a foamy appearing cytoplasm.
• Eccrine Sweat Glands - coiled, tubular sweat-producing glands and ducts with simple or stratified cuboidal epithelium.
• Arrector Pili Muscles - small muscles (#1,#2) attached to hair follicles that cause hair to stand on end.