◾Sebaceous glands are small, oil-producing exocrine glands present in the skin.
◾ They are usually attached to hair follicles and secrete sebum, an oily substance.
🔹 Key Term: Sebum – An oily secretion that lubricates skin and hair.
Functions
◾Lubrication: Keeps skin and hair soft and prevents dryness.
◾Waterproofing: Forms a protective barrier to reduce water loss from the skin.
◾Antibacterial: Sebum contains fatty acids that help inhibit microbial growth.
◾Thermoregulation support: Aids in temperature control by keeping skin flexible.
Types / Classification
◾ Based on location:
✔️ Follicular sebaceous glands: Most common, open into hair follicles.
✔️ Free sebaceous glands: Open directly onto skin (e.g., lips, eyelids, areola, genital areas).
◾ Specialized Sebaceous Glands:
✔️Meibomian glands: Eyelids (produce oil for the tear film).
✔️ Fordyce spots: Visible sebaceous glands without hair (e.g., lips, genitals).
✔️ Montgomery glands: Around the areola (help in breastfeeding).
✔️ Tyson glands: Penis foreskin.
Examples (Location-Based)
◾Common Locations: Face, scalp, chest, back.
◾Absent In: Palms of hands and soles of feet.
📍 Face and scalp have the highest concentration of sebaceous glands.
Differences (Compared with Endocrine Glands)
| Feature | Sebaceous Glands (Exocrine) | Endocrine Glands |
|---|---|---|
| Duct System | Present (secreted through ducts) | Absent (ductless) |
| Secretion Target | Onto the skin surface or into hair follicles | Into the bloodstream |
| Secretion Type | Sebum (oil) | Hormones |
| Example | Sebaceous glands, sweat glands | Pituitary, thyroid, and adrenal |
Exam Facts / One-liners / MCQ Points
✅ Sebaceous glands are exocrine glands (secrete via ducts).
✅ Sebum is the oily secretion that prevents skin dryness and bacterial growth.
✅ These glands are mostly associated with hair follicles.
✅ Most numerous on face and scalp; absent on palms and soles.
✅ Overactive sebaceous glands can lead to acne.
✅ Blocked sebaceous glands may cause cysts or conditions like sebaceous hyperplasia.
✅ Specialized sebaceous glands include Meibomian, Montgomery, Fordyce, and Tyson glands.
