Most animals display internal and/or external left–right asymmetry. The gastropod Lymnaea stagnalis has both sinistral and dextral snails within a species; the chirality is hereditary, but the gene(s) and mechanisms for handedness-determination are not yet identified. In L. stagnalis, the chiral blastomere arrangement at the eight-cell stage is now shown to determine left–right asymmetry throughout development, acting upstream of the Nodal signalling pathway.
- Reiko Kuroda
- Bunshiro Endo
- Miho Shimizu
