Cleavage in ctenophora
<a href="//commons.wikimedia.org/wiki/User:Kaidor" title="User:Kaidor">Kaidor</a>
<a rel="nofollow" class="external autonumber" href="https://openi.nlm.nih.gov/imgs/512/64/2959043/PMC2959043_2041-9139-1-10-2.png">[1]</a>