What does exocytic mean?
"Exocytic" is an adjective from cell biology that describes processes and structures involved in exocytosis — the mechanism by which a cell exports material to its exterior. Inside the cell, cargo such as hormones, neurotransmitters, enzymes, or waste is packed into small membrane-bound sacs called vesicles; in an exocytic event, such a vesicle travels to the cell's outer surface, merges with the surrounding membrane, and spills its contents outside. Scientists use the term attributively, as in "exocytic pathway", "exocytic vesicle", or "exocytic fusion", when tracing how molecules leave a cell. It is essentially the reverse of endocytosis, which imports material into the cell. Though rare outside laboratory and clinical writing, the word underpins some of biology's most vital routines: every nerve impulse, hormone surge, and digestive secretion depends on exocytic delivery.
adjectiveRelating to or involving exocytosis: the process by which a cell releases substances by fusing membrane-bound vesicles with its outer membrane. Used chiefly in cell biology to describe vesicles, pathways, or events that carry material out of the cell.
- Of or relating to exocytosis, the cellular process of discharging material by fusing intracellular vesicles with the plasma membrane.
"Neurotransmitter release depends on the exocytic fusion of synaptic vesicles with the presynaptic membrane."
"Insulin leaves the pancreatic beta cells through the exocytic pathway."
"The researchers tracked fluorescent markers through each stage of the exocytic cycle."
Every thought you've ever had was delivered by an exocytic event: your neurons release their chemical messages one vesicle at a time.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of exocytic
"Exocytic" derives from "exocytosis", coined in 20th-century cell biology from Greek roots: "exo-", meaning 'outside', and "cyto-", from Greek "kytos", meaning 'hollow vessel' or 'cell', joined to the suffix "-ic". The word belongs to a large family of biological terms built on "cyto-", including cytoplasm and cytokinesis, and pairs directly with its antonym "endocytic", formed with the Greek prefix "endo-", meaning 'within'. Its adoption followed the electron-microscope era, when researchers could finally observe how cells discharge material via fused vesicles.
Related word forms
How exocytic is actually used
Strictly technical vocabulary confined to cell biology, biochemistry, and medicine; rarely encountered outside scientific literature and textbooks. Almost always appears attributively before a noun such as 'pathway', 'vesicle', 'fusion', or 'event'. The related noun 'exocytosis' and verb 'exocytose' are more commonly used than the adjective itself.
Easily confused with exocytic
Endocytic describes the opposite process — bringing material into the cell via vesicles — whereas exocytic describes releasing material out of it.