Arnolds Willem J A, van den Biggelaar Jo A M, Verdonk Nico H
Zoological Laboratory, State University of Utrecht, Padualaan 8, 3508 TB, Utrecht, The Netherlands.
Wilehm Roux Arch Dev Biol. 1983 Mar;192(2):75-85. doi: 10.1007/BF00848483.
In equally cleaving gastropods, the interactions between micromeres and macromeres involved in the determination of the mesentoblast mother cell (3D) were studied by changing the spatial arrangement of the micromeres by deleting one first quartet micromere or its progeny. A fixed relation was found between the deletion site and the place of origin of 3D; therefore, a fixed relation also exists in the configuration of the three remaining first quartet micromeres and the 3D. These results argue against the possibility that the animal-vegetal interactions do not choose between macromeres, but only permit the expression of a choice already made in another way and at another moment. The results are consistent with a stochastic model in which accidental differences between the macromeres in the number or extent of contacts with first quartet micromeres play a discriminating role during micromere - macromere interactions, that lead to 3D determination.Embryos which lack a given first quartet micromere show a total absence of regulation in the larval head pattern; only the cephalic plates show regulative abilities while forming the adult head structures. Therefore, in later stages new activating and restraining factors seem to play a part in the head development.
在均等分裂的腹足类动物中，通过删除一个第一四分体小分裂球或其后代来改变小分裂球的空间排列，研究了参与中胚层母细胞（3D）决定过程的小分裂球和大分裂球之间的相互作用。发现删除位点与3D的起源位置之间存在固定关系；因此，在其余三个第一四分体小分裂球和3D的构型中也存在固定关系。这些结果反驳了动物-植物相互作用不是在大分裂球之间进行选择，而只是允许以另一种方式和在另一个时刻已经做出的选择得以表达的可能性。这些结果与一个随机模型一致，在该模型中，大分裂球在与第一四分体小分裂球接触的数量或范围上的偶然差异在小分裂球-大分裂球相互作用中起区分作用，从而导致3D的决定。缺乏特定第一四分体小分裂球的胚胎在幼虫头部模式中完全没有调节能力；只有头板在形成成体头部结构时表现出调节能力。因此，在后期阶段，新的激活和抑制因子似乎在头部发育中起作用。
