Extrusomes are membrane-bound structures in some eukaryotes which, under certain conditions, discharge their contents outside the cell. There are a variety of different types, probably not homologous, and serving various functions.

Notable extrusomes include mucocysts, which discharge a mucous mass sometimes used in cyst formation, and trichocysts, which discharge a fibrous rod.[1] The stinging nematocysts found in Cnidarian animals may be regarded as extrusomes as well. Extrusomes found in dinoflagellates are important in the formation of red and black tides.[citation needed] Ancoracysta twista, a Provoran eukaryote, immobilises its prey using a type of extrusome named an ancoracyst.[2]


  1. ^ Lynn D (2008). "Glossary". The Ciliated Protozoa: Characterization, Classification, and Guide to the Literature. Springer. p. 39. ISBN 978-1-4020-8239-9. Retrieved 16 January 2018.
  2. ^ Janouškovec J, Tikhonenkov DV, Burki F, Howe AT, Rohwer FL, Mylnikov AP, Keeling PJ. "A New Lineage of Eukaryotes Illuminates Early Mitochondrial Genome Reduction", Current Biology 2017, doi:10.1016/j.cub.2017.10.051