※ Germ plasm/Polar granule introduction

    Germ plasm, a specialized cytoplasm present at the posterior of the early Drosophila embryo, is necessary and sufficient for germ cell formation. Germ plasm is rich in mitochondria and contains electron dense structures called polar granules, which are necessary for germ line formation and might be related to P bodies (1). In zebra-fish, germ plasm are proved to be related phase-separated structures. Throughout development, many germ cell-specific mRNAs and proteins condense as a single large aggregate (Bb), which disperse throughout oogenesis and upon fertilization accumulates again into relatively large assemblies (Gp) (2). In many organisms, germ cell fate is imposed on cells through the cytoplasmic inheritance of germ plasm (Gp) (2).

Reference
1. Roovers, E. F., Kaaij, L. J. T., Redl, S., Bronkhorst, A. W., Wiebrands, K., de Jesus Domingues, A. M., Ketting, R. F. (2018) Tdrd6a Regulates the Aggregation of Buc into Functional Subcellular Compartments that Drive Germ Cell Specification. Dev Cell, 46(3), 285-301 e289. PMID: 30086300
2. Thomson, T., Liu, N., Arkov, A., Lehmann, R., & Lasko, P. (2008) Isolation of new polar granule components in Drosophila reveals P body and ER associated proteins. Mech Dev, 125(9-10), 865-873. PMID: 18590813