Gotow T, Hashimoto P H
Department of Anatomy, Osaka University Medical School, Japan.
Cell Tissue Res. 1989 Apr;256(1):53-64. doi: 10.1007/BF00224718.
Membrane-bounded organelles possessing cisternae, i.e., rough endoplasmic reticulum and Golgi apparatus, in immature rat central neurons were examined by quick-freeze and deep-etch techniques to see how their intracisternal structures are organized and how ribosomes are associated with the membrane of the endoplasmic reticulum. Cisternae of endoplasmic reticulum, 60-100 nm wide, were bridged with randomly-distributed strands (trabecular strands, 12.5 nm in mean diameter). Luminal surfaces of cisternae of the endoplasmic reticulum were decorated with various-sized globular particles, some as small as intramembrane particles, and others as large as granules formed by soluble proteins seen in the cytoplasm. A closer examination revealed much thinner strands (3.3 nm in mean diameter). Such thin strands were short, usually winding toward the luminal surface, and sometimes touching the luminal surface with one end. Ribosomes appeared to be embedded into the entire thickness of cross-fractured membranes of endoplasmic reticulum, that is, their internal portions appeared to be situated at almost the same level as the cisternal luminal surface. From the internal portion of ribosomes, single thin strands occasionally protruded into the lumen, suggesting that these thin strands were newly synthesized polypeptides. A horizontal separation within ribosomes appeared to occur at the same level as the hydrophobic middle of the membrane of the endoplasmic reticulum. Interiors of the Golgi apparatus cisternae, which were much narrower than cisternae of endoplasmic reticulum, were similarly bridged with trabecular strands, but the Golgi trabecular strands were thinner and more frequent. Their cisternal lumina were also dotted with globular particles. No identifiable profiles corresponding to the thin strands in the endoplasmic reticulum were observed. Golgi cisternae showed a heterogeneous distribution of membrane granularity; the membrane in narrow cisternal space was granule-rich, while that in expanded space was granule-poor, suggesting a functional compartmentalization of the Golgi cisternae.
采用快速冷冻和深度蚀刻技术，对未成熟大鼠中枢神经元中具有扁平囊的膜结合细胞器，即粗面内质网和高尔基体进行了检查，以了解其扁平囊内结构是如何组织的，以及核糖体如何与内质网膜相关联。内质网的扁平囊宽60 - 100纳米，由随机分布的链（小梁状链，平均直径12.5纳米）相连。内质网扁平囊的腔表面装饰有各种大小的球状颗粒，一些小如膜内颗粒，另一些大如细胞质中可溶性蛋白质形成的颗粒。进一步检查发现有更细的链（平均直径3.3纳米）。这种细链很短，通常向腔表面缠绕，有时一端接触腔表面。核糖体似乎嵌入内质网交叉断裂膜的整个厚度中，也就是说，它们的内部部分似乎与扁平囊腔表面处于几乎相同的水平。从核糖体内部，偶尔有单条细链伸入腔内，表明这些细链是新合成的多肽。核糖体内部的水平分离似乎发生在内质网膜疏水中部的同一水平。高尔基体扁平囊比内质网扁平囊窄得多，同样由小梁状链相连，但高尔基体的小梁状链更细且更密集。它们的扁平囊腔也布满了球状颗粒。未观察到与内质网中细链相对应的可识别轮廓。高尔基体扁平囊显示出膜颗粒度的不均匀分布；狭窄扁平囊腔内的膜富含颗粒，而扩张空间内的膜颗粒较少，这表明高尔基体扁平囊存在功能分区。
