Emergence of Bilateral Symmetry from Chiral Components in the Planarian Epidermis

Most animals exhibit mirror-symmetric body plans, yet the molecular constituents from which they are formed are often chiral. In planarian flatworms, centrioles are arranged in a bilaterally symmetric pattern across the ventral epidermis. Here, we found that this pattern is generated by a network of centrioles with prominent left-right asymmetric properties. We identify centriole components required for establishing left-right asymmetric connections between centrioles and balancing their effects to align centrioles along polarity fields. We show that the asymmetry of the network is also compensated by specific interactions of its components with polarity cues on the left and right sides of the planarian body. Our findings shed new light on how bilateral symmetry can emerge from chiral cellular organizations.