The correct assembly, migration, and segregation of the mRNAs of the germ plasm during the first cell divisions are intimately connected to the cytoskeleton and cytokinesis.RhoA is a key regulator of germ plasm localization during the first two cell division cycles in zebrafish embryos. Pharmacological inhibition of RhoA and his effector ROCK affected the correct assembly of microtubules in the cleavage furrow with the concomitant abnormal localization of germ plasm mRNAs. The inhibition of RhoA/ROCK pathway caused a significant decrease in the germ cell population later in development.