bone and cartilage stained skeletal preps of stage 58 xenopus laevis metamorphs heat shock applied at limb bud stages 48, 49, 50, 52 as in 10.1016/j.mod.2015.10.003 Wang et al 2015.Prehallux (blue cartilage indicated by arrow and seems present in all samples where digit 1 is preserved.