According to the authors, Plasmid templates were used to generate digoxygenin antisense riboprobes: Lhx2a (S. Richter). As information provided was insufficient to verify exact sequence used to synthesize probe, the sequence below was obtained from NCBI (acc # NM_204889).
Images and probe sequence provided by Claire Anderson. The probe was supplied by Tsutomu Nohnoa. Related paper: Anderson C, Hill B, Lu HC, Moverley A, Yang Y, Oliveira NMM, Baldock RA, Stern CD. A 3D molecular atlas of the chick embryonic heart. Dev Biol. 2019 Dec 1;456(1):40-46. doi: 10.1016/j.ydbio.2019.07.003. Epub 2019 Jul 5.