show Abstracthide AbstractThe affinity of the echinoderm pentaradial body plan with that of the ancestral bilateral symmetry remains one of the biggest zoological puzzle. Here, we revisited this classical zoological problem using RNA tomography and HCR in situ hybridization in the sea star Patiria miniata. Overall design: Young Patiria miniata (~2cm) sectioned into indiviual arms, each of which was cryo micro-sectioned into 8-22 sections across 3 sectionng dimensions (Proximo-disal, oral-aboral, and left-right) full length transcriptomic data was gathered on each section. Addionally HRC insitu hybridizations were performed to provide higher resolution information for specific developementally imporant genes.