Extrusomes are membrane-bound structures in some
eukaryote
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacter ...
s 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
trichocyst
A trichocyst is an organelle found in certain ciliates and dinoflagellate
The dinoflagellates ( Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the ...
s, which discharge a fibrous rod.
The stinging
nematocyst
A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this ce ...
s found in
Cnidaria
Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter.
Their distinguishing feature is cnidocytes, specialized cells that ...
n animals may be regarded as extrusomes as well. Extrusomes found in
dinoflagellate
The dinoflagellates ( Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
s are important in the formation of red and black tides.
References
External links
Image: extrusome (labeled EX)
Organelles
{{Protist structures