Nieuwkoop P D
Hubrecht Laboratory, Utrecht, Holland.
Wilhelm Roux Arch Entwickl Mech Org. 1970 Jun;166(2):105-123. doi: 10.1007/BF00576988.
Strong Li treatment leads to auto-activation of blastula and gastrula ectoderm due to lethal and sublethal cytolysis, resulting in adirect meso- and endodermization of the ectoderm. In contrast, a mild Li treatment-0.04 M LiCl in Holtfreter solution for only two hours-which does not show cytolizing effects, has no or only a weak mesodermizing effect upon blastula ectoderm. However, when the explant contains endoderm as well the same treatment leads to a marked transformation of ectoderm into mesoderm and subsequently into endoderm (vegetalization). Thisindirect action of the Li ion under "physiological" conditions apparently represents an enhancement of the normally occurring mesoderm formation from the ectodermal component of the blastula under the inducing action of the endodermal component and its subsequent transformation into endodermal structures, probably due to a rise in competence. The question is raised in how far the direct meso-and endodermization of gastrula ectoderm by heterogeneous inductors is open to the same criticsm as in the case of auto-activation of the ectoderm by a strong Li treatment. Finally, the experiments of Ave, Kawakami and Sameshima (1968) are briefly discussed.
高浓度锂处理会因致死性和亚致死性细胞溶解导致囊胚和原肠胚外胚层的自动激活，从而使外胚层直接中胚层化和内胚层化。相比之下，轻度锂处理——在霍尔特弗雷特溶液中用0.04 M LiCl处理仅两小时——不会产生细胞溶解作用，对囊胚外胚层没有或只有微弱的中胚层化作用。然而，当外植体也包含内胚层时，相同的处理会导致外胚层显著转化为中胚层，随后再转化为内胚层（植物化）。锂离子在“生理”条件下的这种间接作用显然是在中胚层成分的诱导作用下，囊胚外胚层成分中正常发生的中胚层形成及其随后向内胚层结构转化的增强，这可能是由于感受性的提高。问题在于，原肠胚外胚层通过异种诱导剂直接中胚层化和内胚层化在多大程度上会受到与高浓度锂处理使外胚层自动激活情况相同的批评。最后，简要讨论了阿韦、川上和ameshima（1968年）的实验。
