Which type of secretion releases secretory products via exocytosis?

• A. Merocrine (secretory vesicles released via exocytosis)
• B. Apocrine
• C. Holocrine
• D. Endocrine

Answer: (A)

Merocrine secretion is the process where secretory products are released by vesicles that fuse with the cell membrane and exocytose their contents into a duct or exterior space, while the cell itself remains intact and continues to function. This vesicle-to-membrane fusion is the hallmark of releasing material without losing cellular material, which is why it’s described as exocytosis. Sweat glands and goblet cells commonly use this mode, making their secretions appear as distinct granules or mucus released through the duct.

In contrast, apocrine secretion involves shedding a portion of the cell’s apical cytoplasm along with the secretory product, holocrine secretion releases the entire cell which disintegrates to release its content, and endocrine secretion delivers products into the interstitial space and bloodstream rather than into a duct.