Editing Cnidocyte (section)

=== Modes of renewal ===
[[File:Cnidocyte development in hydra.png|left|thumb|400x400px|Overview of the development of the 4 different capsule types of Hydra polyps.]]
In [[Hydra (genus)|Hydra]] [[polyps]], cnidocytes differentiate from a specific population of [[stem cells]], the interstitial cells (I-cells) located within the body column. Developing nematocysts first undergo multiple rounds of [[mitosis]] without [[cytokinesis]], giving rise to nematoblast nests with 8, 16, 32 or 64 cells. After this expansion phase, [[nematoblasts]] develop their capsules. Nests separate into single nematocysts when the formation of the capsule is complete.<ref name="Beckmann" /> Most of them migrate to the tentacles where they are incorporated into battery cells, which hold several nematocysts, and [[neurons]]. Battery cells coordinate firing of nematocysts.

In the [[hydrozoan]] jellyfish ''[[Clytia hemisphaerica]]'', nematogenesis takes place at the base of the tentacles, as well as in the [[manubrium]]. At the base of the tentacles, nematoblasts proliferate then differentiate along a proximal-distal [[gradient]], giving rise to mature nematocytes in the tentacles through a conveyor belt system.<ref>{{Cite journal|last1=Denker|first1=Elsa|last2=Manuel|first2=Michaël|last3=Leclère|first3=Lucas|last4=Le Guyader|first4=Hervé|last5=Rabet|first5=Nicolas|date=2008-03-01|title=Ordered progression of nematogenesis from stem cells through differentiation stages in the tentacle bulb of Clytia hemisphaerica (Hydrozoa, Cnidaria)|journal=Developmental Biology|volume=315|issue=1|pages=99–113|doi=10.1016/j.ydbio.2007.12.023|issn=1095-564X|pmid=18234172|doi-access=}}</ref>

In the Anthozoan sea anemone ''[[Nematostella vectensis]]'', nematocytes are thought to develop throughout the animal from epithelial progenitors.<ref>{{Cite journal|last1=Babonis|first1=Leslie S.|last2=Martindale|first2=Mark Q.|date=2017-09-04|title=PaxA, but not PaxC, is required for cnidocyte development in the sea anemone Nematostella vectensis|journal=EvoDevo|volume=8|pages=14|doi=10.1186/s13227-017-0077-7|issn=2041-9139|pmc=5584322|pmid=28878874 |doi-access=free }}</ref> Furthermore, a single regulatory gene that codes for the transcription factor ZNF845 also called CnZNF1 promotes the development of a cnidocyte and inhibits the development of a RFamide producing neuron cell.<ref name=":2">{{Cite journal |last1=Babonis |first1=Leslie S. |last2=Enjolras |first2=Camille |last3=Ryan |first3=Joseph F. |last4=Martindale |first4=Mark Q. |date=2022-05-10 |title=A novel regulatory gene promotes novel cell fate by suppressing ancestral fate in the sea anemone Nematostella vectensis |journal=Proceedings of the National Academy of Sciences |language=en |volume=119 |issue=19 |pages=e2113701119 |doi=10.1073/pnas.2113701119 |doi-access=free |issn=0027-8424 |pmc=9172639 |pmid=35500123|bibcode=2022PNAS..11913701B }}</ref> This gene evolved in the stem cnidarian through domain shuffling.<ref name=":2" />