Induction of notochord during ascidian embryogenesis.
Induction of notochord during ascidian embryogenesis.
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海鞘胚胎发生过程中脊索的诱导。
DOI：
10.1006/dbio.1994.1315
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发表时间：
1994
影响因子：
2.7
通讯作者：
Hiroki Nishida
中科院分区：
文献类型：
--
作者：
Yuki Nakatani;Hiroki Nishida
孤生海鞘蝌蚪幼虫尾部有40个脊索细胞。其中，32个位于尾部前部和中部，来自A线卵裂球，8个位于尾部后部，来自B线卵裂球。以前的实验，涉及连续解离的子卵裂球从第一次分裂到110细胞的阶段表明，细胞的相互作用可能参与脊索细胞的形成。在本研究中，从32细胞胚胎分离的推测脊索卵裂球没有发育脊索的特征。这些结果表明，细胞的相互作用可能需要的命运规格的脊索，也就是说，脊索的形成发生作为一个结果的诱导相互作用的卵裂球。为了证实诱导参与脊索的决定，并确定诱导卵裂球，假定脊索卵裂球在32-细胞阶段共分离或重组与周围的卵裂球之一，在一系列的实验。结果表明，对于A-线前体，脊索分化发生的诱导影响的结果，从植物卵裂球，包括推定内胚层卵裂球和推定脊索卵裂球本身。还表明脊索的诱导在64细胞阶段完成，并且诱导相互作用必须在32细胞阶段的卵裂球解压缩之前启动。海鞘是尾索动物门，与脊椎动物关系密切。众所周知，在脊椎动物中，诱导相互作用在脊索的确定中发挥着至关重要的作用。因此，看来脊索的诱导在脊索动物门中是普遍的。
The tadpole larva of solitary ascidians has 40 notochord cells in its tail. Of these cells, 32 in the anterior and middle part of the tail are derived from the A-line blastomeres, while 8 in the posterior part of the tail originate from the B-line blastomeres. Previous experiments involving continuous dissociation of daughter blastomeres from the first cleavage to the 110-cell stage suggested that cellular interactions may be involved in the formation of notochord cells. In the present study, the presumptive-notochord blastomeres isolated from the 32-cell embryos did not develop features of notochord. These results suggest that cellular interactions may be required for the fate specification of notochord, that is to say, notochord formation occurs as a result of inductive interaction between blastomeres. In order to confirm the involvement of induction in the determination of notochord and to identify the inducer blastomeres, the presumptive-notochord blastomeres at the 32-cell stage were coisolated or recombined with one of the surrounding blastomeres in a series of experiments. The results suggested that, for the A-line precursors, notochord differentiation occurs as the result of an inductive influence from vegetal blastomeres that include the presumptive-endoderm blastomeres and the presumptive-notochord blastomeres themselves. It was also suggested that induction of notochord is complete by the 64-cell stage and that inductive interactions have to be initiated before the decompaction of blastomeres during the 32-cell stage. Ascidians are Urochordata and are closely related to vertebrates. In vertebrates, it is well known that inductive interactions play a crucial role in the determination of notochord. It appears, therefore, that induction of notochord is common throughout the phylum Chordata.