The Collaborative International Dictionary of English v.0.48:

Cytula \Cyt"u*la\ (s?t"?-l?), n. [NL., fr. Gr. ky`tos a hollow
   vessel.] (Biol.)
   The fertilized egg cell or parent cell, from the development
   of which the child or other organism is formed. --H[ae]ckel.
   [1913 Webster]