Symmetry-breaking in the C. elegans embryo is driven by asymmetric flows of actomyosin which transport PAR protein clusters away from the posterior pole thereby helping to set up the anterior posterior axis of the developing animal. Here transient PAR-3 clusters (red) can be seen streaking along the surface of the cell in response to actomyosin flows before dissipating as the cell enters mitosis. Previous positions are time-coded and shown in cyan yielding comet tails, which highlight the directionality of cluster movement.
