Histology Lecture 3: Glandular Epithelia Classification

Types of Glands and Their Secretions

• Exocrine Glands: Release secretory products by exocytosis, involving vesicle fusion with the plasma membrane to expel substances.

• Glands with Ducts: Secrete products into a duct, which opens to the surface of covering or lining membranes, facilitating direct delivery of substances (e.g., sweat glands, salivary glands).

• Endocrine Glands: Ductless glands that release their secretions directly into the surrounding interstitial fluid, allowing hormones to enter the bloodstream for systemic distribution (e.g., thyroid gland, adrenal glands).

• Apocrine Glands: Release secretory products by budding off a portion of the cell, which creates secretion while retaining the rest of the cell (e.g., mammary glands).

• Holocrine Glands: Form secretory products in the cytoplasm and release the entire cell contents upon cell lysis; when the cell dies, it releases its secretions (e.g., sebaceous glands).