Maden M
J Embryol Exp Morphol. 1980 Apr;56:201-9.
The applicability to the amphibian limb of the rule of distal transformation, which states that tissue from any level can only become more distal, has been tested during intercalary regeneration following various types of shift-level transplantation. Following the grafting of distal blastemas to proximal levels, such that part of the presumptive pattern is missing, complete limbs nevertheless formed (Series I). That the intercalated tissue arose entirely from the stump was shown by exchanging blastemas between black and white animals. When the proximal stump was irradiated and its contribution eliminated, intercalary deletions were produced (Series II). This was not due to the inability of irradiated and normal tissue to communicate since irradiated distal blastemas grafted onto proximal stumps still stimulated intercalary regeneration (Series III). When proximal blastemas were grafted to distal levels intercalary regenerates were obtained in about 20% of the cases (Series IV) and under these circumstances the grafted blastema was the sole source of intercalated tissue. The precise structure of these intercalated elements was impossible to ascertain, but it is suggested that they might be of reversed polarity as found in insects. These results are dicussed in relation to similar experiments on the insect limb.
远端转化规则指出，任何水平的组织只能向更远端转化，该规则对两栖动物肢体的适用性已在各种类型的移位水平移植后的间插再生过程中得到检验。将远端芽基移植到近端水平后，由于部分预期模式缺失，但仍形成了完整的肢体（系列I）。通过在黑色和白色动物之间交换芽基表明，间插组织完全来自残端。当近端残端受到辐射并消除其贡献时，会产生间插缺失（系列II）。这并非由于受辐射组织和正常组织无法连通，因为将受辐射的远端芽基移植到近端残端仍能刺激间插再生（系列III）。当近端芽基移植到远端水平时，约20%的情况下可获得间插再生组织（系列IV），在这种情况下，移植的芽基是间插组织的唯一来源。这些间插元件的确切结构无法确定，但有人认为它们可能具有与昆虫中发现的相反极性。结合对昆虫肢体的类似实验对这些结果进行了讨论。
