Karr T L, Alberts B M
J Cell Biol. 1986 Apr;102(4):1494-509. doi: 10.1083/jcb.102.4.1494.
The cytoskeleton of early, non-cellularized Drosophila embryos has been examined by indirect immunofluorescence techniques, using whole mounts to visualize the cortical cytoplasm and sections to visualize the interior. Before the completion of outward nuclear migration at nuclear cycle 10, both actin filaments and microtubules are concentrated in a uniform surface layer a few micrometers deep, while a network of microtubules surrounds each of the nuclei in the embryo interior. These two filament-rich regions in the early embryo correspond to special regions of cytoplasm that tend to exclude cytoplasmic particles in light micrographs of histological sections. After the nuclei in the interior migrate to the cell surface and form the syncytial blastoderm, each nucleus is seen to be surrounded by its own domain of filament-rich cytoplasm, into which the cytoskeletal proteins of the original surface layer have presumably been incorporated. At interphase, the microtubules seem to be organized from the centrosome directly above each nucleus, extending to a depth of at least 40 microns throughout the cortical region of cytoplasm (the periplasm). During this stage of the cell cycle, there is also an actin "cap" underlying the plasma membrane immediately above each nucleus. As each nucleus enters mitosis, the centrosome splits and the microtubules are rearranged to form a mitotic spindle. The actin underlying the plasma membrane spreads out, and closely spaced adjacent spindles become separated by transient membrane furrows that are associated with a continuous actin filament-rich layer. Thus, each nucleus in the syncytial blastoderm is surrounded by its own individualized region of the cytoplasm, despite the fact that it shares a single cytoplasmic compartment with thousands of other nuclei.
利用整体装片观察皮层细胞质，利用切片观察内部结构，通过间接免疫荧光技术对早期未细胞化的果蝇胚胎的细胞骨架进行了研究。在第10个核周期向外核迁移完成之前，肌动蛋白丝和微管都集中在几微米深的均匀表层，而微管网围绕着胚胎内部的每个细胞核。早期胚胎中这两个富含细丝的区域对应于细胞质的特殊区域，在组织学切片的光学显微镜图像中，这些区域往往会排斥细胞质颗粒。内部的细胞核迁移到细胞表面并形成合胞体胚盘后，每个细胞核都被其自身富含细丝的细胞质区域所包围，原来表层的细胞骨架蛋白大概已整合到这个区域中。在间期，微管似乎是从每个细胞核正上方的中心体组织而来，延伸到整个皮层细胞质区域（周质）至少40微米的深度。在细胞周期的这个阶段，每个细胞核正上方的质膜下方还有一个肌动蛋白“帽”。当每个细胞核进入有丝分裂时，中心体分裂，微管重新排列形成有丝分裂纺锤体。质膜下方的肌动蛋白散开，相邻的紧密排列的纺锤体被与富含肌动蛋白丝的连续层相关的瞬时膜沟隔开。因此，合胞体胚盘中的每个细胞核都被其自身特有的细胞质区域所包围，尽管它与数千个其他细胞核共享一个单一的细胞质区室。
