This asymmetry can be restricted to a specific organ or feature, as in the crab claws, or be expressed throughout the entire body as in snails.
[3] The name of the LR organiser varies between species, and thus includes the node in mice, the gastrocoel roof plate in frog and Kupffer’s vesicle in zebrafish.
[8] Recently, work has shown that the Nodal-Pitx2 pathway is present and functional in the non-vertebrate deuterostomes (tunicates, sea urchins).
At earlier stages, similar H+/K+ ATPase ion channels are reported to be necessary for correct left-right patterning.
[10] Because protostomes appear to also express Nodal on their right side instead of the left (discussed below), some have suggested that this lends further evidence for the dorsoventral inversion hypothesis.
[12] While D. melanogaster and nematode Caenorhabditis elegans do show left-right asymmetry, the Nodal signaling pathway itself is absent in Ecdysozoa.
[12] Instead, cytoskeletal regulators such as Myo31DF, a type ID unconventional myosin, have been found to control left-right asymmetry in organ systems such as genitalia.
[20] In limpets (gastropods without coiled shells) dpp is expressed symmetrically in Patella vulgata and Nipponacmea fuscoviridis.
[20] Additionally, in N. fuscoviridis, dpp has been shown to drive cell proliferation[21] Upstream of Nodal, Lsdia1/2 have been implicated in controlling L. stagnalis chirality.