Usui Noriko, Yoneda Mitsuki
Department of Anatomy, Teikyo University School of Medicine, Kaga, Itabashi-ku, Tokyo 173, Japan.
Department of Zoology, Faculty of Science, Kyoto University, Kyoto 606, Japan.
Dev Growth Differ. 1982;24(5):453-465. doi: 10.1111/j.1440-169X.1982.00453.x.
Cortices of sea-urchin eggs were studied by electron microscopy to identify the structure responsible for the rise in tension at the egg surface prior to cleavage. During anaphase the tension increased and fine filaments of 70-90 Å in diameter appeared in the cell cortex forming a thin mesh-work beneath the cell membrane. The meshwork spread all around the egg cortex without reference to the mitotic axis and the number of filaments seemed to increase up to telophase. Immediately before appearance of the cleavage furrow, the meshwork in the anticipated furrow region became dense. As the furrow appeared the tension began to decrease and the meshwork disappeared. In the progressing furrow region fine filaments of the same size as that of the meshwork-filament were oriented in a bundle to form a contractile ring. Treatment with cytochalasin B suppressed both the tension increase and the formation of the filamentous meshwork. These results suggest that the component filament of the meshwork is an actin microfilament, and that the tension increase at anaphase is due to formation of a meshwork of actin microfilaments from which a contractile ring is subsequently derived at late telophase.
通过电子显微镜研究海胆卵的皮质，以确定在卵裂前导致卵表面张力升高的结构。在后期，张力增加，直径为70 - 90埃的细丝出现在细胞皮质中，在细胞膜下方形成一个薄的网络。该网络在卵皮质周围扩散，与有丝分裂轴无关，细丝数量似乎一直增加到末期。就在分裂沟出现之前，预期沟区域的网络变得密集。随着沟的出现，张力开始降低，网络消失。在正在形成的沟区域，与网络细丝大小相同的细丝束状排列形成收缩环。用细胞松弛素B处理可抑制张力增加和丝状网络的形成。这些结果表明，网络的组成细丝是肌动蛋白微丝，后期张力增加是由于肌动蛋白微丝网络的形成，随后在末期后期从中衍生出收缩环。
