Going with the flow: an elegant model for symmetry breaking.

The entry of the sperm centrosome polarizes the anterior-posterior axis of the C. elegans zygote by inducing the formation of complementary cortical Par protein domains. Recent papers from the Seydoux and Grill laboratories (Goehring et al., 2011b and Motegi et al., 2011) reveal how two different symmetry-breaking mechanisms produce the same final pattern through interactions between Par proteins.