Saito T, Kamimoto M, Miyake A, Yamaha E, Suzuki T, Nakatsuji N, Nakatsuji T
Department of Marine Biology, Graduate School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka, Japan.
Int J Dev Biol. 2001 Jun;45(4):661-8.
Isolation of cleavage-stage blastomeres and the study of their developmental potential has been used extensively for analyzing the mechanisms of embryogenesis in vertebrates, including amphibians and echinoderms. We devised a method to isolate 8-cell stage blastomeres in the teleost, shiro-uo, by utilizing its unique cleavage pattern of the horizontal 3rd cleavage plane. Removal of all the upper blastomeres at the 8-cell stage allowed almost normal embryogenesis from the remaining lower blastomeres and yolk cell mass. Isolated upper or lower blastomeres formed vesicles and spherical bodies, which later showed morphological changes during cultivation. Mesoderm formation was detected not only in the cultivated lower blastomeres or whole blastomeres but also in the upper blastomeres isolated from the yolk cell mass at the 8-cell stage, although at a lower frequency than the lower blastomeres. These results indicated the presence of very early signaling for mesoderm induction, which is independent from the currently postulated signals from the yolk syncytial layer at later stages. This also indicated non-equivalence or differentiation of the blastomeres from the very early cleavage stage in teleost embryos.
卵裂期卵裂球的分离及其发育潜能的研究已被广泛用于分析脊椎动物（包括两栖动物和棘皮动物）的胚胎发生机制。我们设计了一种方法，利用硬骨鱼白肌银鱼独特的水平第三次卵裂面的卵裂模式，分离其8细胞期的卵裂球。在8细胞期去除所有上部卵裂球后，剩余的下部卵裂球和卵黄细胞团几乎能正常胚胎发育。分离的上部或下部卵裂球形成囊泡和球体，在培养过程中它们随后会出现形态变化。中胚层的形成不仅在培养的下部卵裂球或整个卵裂球中被检测到，在8细胞期从卵黄细胞团中分离出的上部卵裂球中也被检测到，尽管其频率低于下部卵裂球。这些结果表明存在非常早期的中胚层诱导信号，该信号独立于目前假定的后期来自卵黄合胞体层的信号。这也表明硬骨鱼胚胎从非常早期的卵裂阶段开始，卵裂球就存在不等价性或分化。
