Fig. 1.

Stages of RNP segregation leading to germ plasm aggregates at the furrow. Radial astral microtubule growth results in the outward movement of RNPs, which begin a process of pre-aggregation even prior to furrow formation. During cell division, the same process, but now driven by microtubules from a bipolar spindle (not shown), results in the RNP recruitment at the furrow. Medial-to-distal movement along the furrow generates compact masses at the furrow distal ends. The process is systematically repeated through the early cell divisions, although only the largest four germ plasm masses, corresponding to those at the first and second cleavage furrows, are stable (Eno and Pelegri, 2013, 2016).