Which feature is unique to holocrine secretion?

• A. Nuclei condense and cells fragment (pyknosis)
• B. Secretions released by exocytosis without cytoplasm loss
• C. Secretions exit through a duct system
• D. Secretions released with intact cell scope

Answer: (C)

Holocrine secretion is defined by the secretory cell dying to release its product. The entire secretory cell contents are discharged as the cell ruptures, so you get secretions mixed with cell debris in the lumen. Because the cell must die to release the product, the nucleus often undergoes condensation and fragmentation (pyknosis) as part of this cell destruction. This mechanism is what sets holocrine secretion apart from other modes: merocrine releases products by exocytosis without any loss of cytoplasm, and apocrine releases APICAL portions of the cell while the rest remains, whereas simply having a duct is a general feature of exocrine glands and not unique to holocrine.