Schwalm Fritz E
Department of Zoology, University of the Witwatersrand, Johannesburg, South Africa.
University of Virginia, Charlottesville, Va.
Wilhelm Roux Arch Entwickl Mech Org. 1969 Mar;162(1):41-55. doi: 10.1007/BF00581545.
Observations on the formation of nuclear membranes and of the changing ultrastructural appearance during mitosis in developing eggs ofLocusta migratoria are reported. 1. Nuclear membranes are formed while the mitotic chromosomes are still in a condensed state. How exactly the membranes are formed, is not yet understood. Vesicles which occur in the interchromosomal space might participate in the membrane formation but they might just as well appear simultaneously with the membranes. 2. Depending on the developmental stage of the egg, differences in the way in which the interphase nucleus is built up, are found. In early cleavage, karyomeres are formed from single chromosomes which are individually covered by a double membrane. These karyomeres expand by uncoiling their chromosomal mass and subsequently fuse to form one nucleus. In embryonic cells of the germinal rudiment the double envelope is formed only after the chromosomes have clustered and have formed the telophase figure. 3. Nuclear membranes are formed in close contact with the condensed chromosomes. Only after the membranes have been built up, the chromosomes lose their electron density. Chromosomes in early developmental stages (cleavage) uncoil in karyomeres, although the mitotic cycle may only have reached anaphase. In cells from later stages (germinal rudiment), where the chromosomes cluster before membrane formation occurs, the membrane formation as well as the uncoiling are postponed to telophase. This behavior may be related to changes in the duration of the mitotic cycle, indicating progressive differentiation. 4. During the growth of karyomeres, chromosomes lose most of their electron density. Dense cores of 0.2 Μ in diameter, however, persist in the karyomeres of cleavage energides and may prove the existence of a chromosomal axis in certain mitotic stages. 5. Nucleoli are not found in karyomeres during early cleavage stages. Prenucleoli are observed to form at telophase in the later stages of development. More prenucleoli seem to occur in telophase than do nucleoli in interphase nuclei.
本文报道了对飞蝗发育卵细胞核膜形成以及有丝分裂过程中超微结构变化的观察结果。1. 核膜在有丝分裂染色体仍处于凝聚状态时形成。膜究竟是如何形成的，目前尚不清楚。染色体间空间中出现的小泡可能参与膜的形成，但它们也可能与膜同时出现。2. 根据卵的发育阶段，发现间期核构建方式存在差异。在早期卵裂时，核粒由单个染色体形成，每个染色体被双层膜单独包裹。这些核粒通过展开其染色体物质而扩大，随后融合形成一个细胞核。在生殖原基的胚胎细胞中，双层包膜仅在染色体聚集并形成末期形态后才形成。3. 核膜与凝聚的染色体紧密接触形成。只有在膜形成后，染色体才失去电子密度。早期发育阶段（卵裂）的染色体在核粒中解旋，尽管有丝分裂周期可能仅处于后期。在后期阶段（生殖原基）的细胞中，染色体在膜形成之前聚集，膜的形成以及解旋都推迟到末期。这种行为可能与有丝分裂周期持续时间的变化有关，表明细胞在进行逐步分化。4. 在核粒生长过程中，染色体失去大部分电子密度。然而，直径为0.2微米的致密核心在卵裂胚细胞的核粒中持续存在，这可能证明在某些有丝分裂阶段存在染色体轴。5. 在早期卵裂阶段的核粒中未发现核仁。在发育后期的末期观察到前核仁形成。末期出现的前核仁似乎比间期核中的核仁更多。
