Authors indicate the probe is from Pourquie et al., 1996 who said they cloned a 600bp fragment with an upstream primer MKEKSKN and 3'RACE. The 5' end fragment is Acc# U40058. The 600 bp sequence here was extracted from XM_419817 using this information.
According to the authors, "Digoxigenin
(DIG)- and fluorescein-labeled riboprobes were synthesized from chick cDNA plasmids..." As information provided was insufficient to verify exact sequence used to synthesize probe,the sequence below was obtained from NCBI (XM_419817).