Sebaceous Glands Anatomy

Sebaceous Glands

• Found all over the body, except for the thick skin
• Branched structure with multiple small sacs called acini, which join together into a short duct and open into a hair follicle
• Form a pilosebaceous unit with a hair follicle
• In areas with no hairs (e.g., penis), the sebaceous gland opens directly onto the skin
• Produce sebum, a complex mixture of lipids, through holocrine secretion
• Sebum helps maintain the stratum corneum and hair shafts, and has weak antibacterial and antifungal properties

Sweat Glands

• Develop as long epidermal invaginations embedded in the dermis
• Two types: eccrine and apocrine sweat glands
• Eccrine sweat glands:
  • Most numerous on the foot soles
  • Coiled and small lumen of both secretory components and ducts
  • Secretory part consists of stratified cuboidal epithelium with three types of cells (dark, clear, and myoepithelial cells)
  • Produce sweat through merocrine secretion
  • Ducts absorb ions from the water to prevent excessive electrolyte loss
  • Function as auxiliary excretory organs, eliminating small amounts of nitrogenous waste and excess salts
• Apocrine sweat glands:
  • Confined to the skin of axillary and perineal regions
  • Development depends on sex hormones
  • Have much larger lumens than eccrine glands
  • Produce pheromones
  • Innervated by adrenergic nerve endings

Mammary Glands

• Compound tubuloalveolar glands
• Consist of 15-25 lobes
• Stroma and parenchyma:
  • Stroma: adipose tissue, dense CT separating the lobules from each other
  • Parenchyma: consists of lactiferous ducts and alveoli
• Before puberty: lactiferous sinuses and lactiferous ducts
• During puberty: high estrogen levels lead to accumulation of adipose CT and increase of lactiferous ducts
• Each lobule consists of several ducts that empty into one terminal duct
• Lactiferous ducts are lined by simple cuboidal epithelium covered by myoepithelial cells
• During pregnancy, the breast undergo enlargement due to hormones
• After pregnancy, prolactin secretion leads to milk production
• Alveoli of lactating glands are lined by cuboidal epithelium with myoepithelial cells
• Secretory cells contain lipid droplets containing caseins (milk proteins) and lactose

Learn about the structure and function of sebaceous glands, including their location, composition, and secretion process. Understand how they relate to hair follicles and skin.