Jones E A, Woodland H R
Cell. 1986 Jan 31;44(2):345-55. doi: 10.1016/0092-8674(86)90769-5.
When do ectodermal cells become specified to form epidermis, that is, become committed to form epidermis when isolated? Animal pole explants of Xenopus cultured in saline from the 8-cell stage onwards express a specific epidermal antigen, whereas vegetal explants do not. The isolated outer layer of ectoderm formed by stage 7 is almost completely specified, the inner layer is only partially so. When are cell associations and cell divisions necessary for epidermal differentiation? Embryos that were either disaggregated or incubated in cytochalasin B after the midblastula stage do not require cell interactions, Ca2+, or cell divisions for epidermal differentiation to occur. Inhibition of mRNA transcription with actinomycin D shows that the epidermal antigen is certainly transcribed by the late gastrula stage (stage 12).
外胚层细胞何时被指定形成表皮，也就是说，何时在分离时就注定会形成表皮？从8细胞期开始在盐溶液中培养的非洲爪蟾动物极外植体表达一种特定的表皮抗原，而植物极外植体则不表达。在第7阶段形成的分离外胚层外层几乎完全被指定，内层只是部分被指定。表皮分化时细胞结合和细胞分裂在何时是必要的？在囊胚中期后进行分散或用细胞松弛素B处理的胚胎，其表皮分化不需要细胞相互作用、Ca2+或细胞分裂。用放线菌素D抑制mRNA转录表明，表皮抗原肯定在原肠胚晚期（第12阶段）就已转录。
