In many animals, maternal cytoplasmic factors called germ plasm regulate gamete production during embryogenesis. Germ plasm is a cytoplasmic determinant composed mainly of RNAs and proteins and is inherited from the mother to the offspring inside the egg (useful reviews: 25413788, 9563905).
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Ikenishi K. Germ plasm in Caenorhabditis elegans, Drosophila and Xenopus. Dev Growth Differ. 1998 Feb;40(1):1-10. doi: 10.1046/j.1440-169x.1998.t01-4-00001.x. PMID: 9563905.