Searls R L, Smith A A
J Exp Zool. 1982 May 1;220(3):343-51. doi: 10.1002/jez.1402200309.
Intact limb buds from stage 19 to 21 embryos differentiate to contain both cartilage and muscle in culture. If the limb ectoderm is removed, the limb mesoderm cells differentiate as cartilage and connective tissue but not as muscle. Intact limb buds from stage 19 embryos differentiate both cartilage and muscle when grafted to the chorioallantoic membrane, but differentiate only cartilage and connective tissue if the ectoderm is removed. The significance of limb ectoderm to muscle differentiation can be observed as late as stage 24. Both the prospective cartilage region and the prospective soft tissue region from the limb of a stage 24 embryo differentiate cartilage and muscle in the presence of limb ectoderm, but differentiate little, if any, muscle in the absence of limb ectoderm. The results indicate that the dorsal and ventral ectoderm have some influence on muscle differentiation.
来自第19至21阶段胚胎的完整肢芽在培养中分化为含有软骨和肌肉。如果去除肢外胚层，肢中胚层细胞分化为软骨和结缔组织，但不分化为肌肉。来自第19阶段胚胎的完整肢芽移植到绒毛尿囊膜上时会分化出软骨和肌肉，但如果去除外胚层则仅分化为软骨和结缔组织。肢外胚层对肌肉分化的重要性直到第24阶段仍可观察到。来自第24阶段胚胎肢体的预期软骨区域和预期软组织区域在有肢外胚层存在时会分化出软骨和肌肉，但在没有肢外胚层时几乎不分化肌肉（如果有分化的话）。结果表明背侧和腹侧外胚层对肌肉分化有一定影响。
