Ubbels G A, Brom T G
Hubrecht Laboratory, International Embryological Institute, Utrecht, The Netherlands.
Adv Space Res. 1984;4(12):9-18. doi: 10.1016/0273-1177(84)90537-4.
The establishment of polarities during early embryogenesis is essential for normal development. Amphibian eggs are appropriate models for studies on embryonic pattern formation. The animal-vegetal axis of the axially symmetrical amphibian egg originates during oogenesis and foreshadows the main body axis of the embryo. The dorso-ventral polarity is epigenetically established before first cleavage. Recent experiments strongly suggest that in the monospermic eggs of the anuran Xenopus laevis both the cytoskeleton and gravity act in the determination of the dorso-ventral polarity. In order to test the role of gravity in this process, eggs will be fertilized under microgravity conditions during the SL-D1 flight in 1985. In a fully automatic experiment container eggs will be kept under well-defined conditions and artificially fertilized as soon as microgravity is reached; eggs and embryos at different stages will then be fixed for later examination. Back on earth the material will be analysed and we will know whether fertilization under microgravity conditions is possible. If so, the relation of the dorso-ventral axis to the former sperm entry point will be determined on the whole embryos; in addition eggs and embryos will be analysed cytologically.
早期胚胎发育过程中极性的建立对正常发育至关重要。两栖类卵是研究胚胎模式形成的合适模型。轴对称的两栖类卵的动物-植物轴在卵子发生过程中形成，并预示着胚胎的主要体轴。背-腹极性在第一次卵裂之前通过表观遗传方式建立。最近的实验有力地表明，在无尾两栖类非洲爪蟾的单精入卵中，细胞骨架和重力都在背-腹极性的决定中起作用。为了测试重力在这个过程中的作用，1985年在SL-D1飞行期间将在微重力条件下使卵受精。在一个全自动实验容器中，卵将被置于明确界定的条件下，一旦达到微重力就进行人工受精；然后将不同阶段的卵和胚胎固定以便日后检查。回到地球后，将对材料进行分析，我们将知道在微重力条件下受精是否可行。如果可行，将在整个胚胎上确定背-腹轴与先前精子进入点的关系；此外，还将对卵和胚胎进行细胞学分析。
