Lindsey J D, Ellisman M H
J Neurosci. 1985 Dec;5(12):3111-23. doi: 10.1523/JNEUROSCI.05-12-03111.1985.
This is the first of three papers describing new components and structural relationships within the neuronal endomembrane system. This system includes: the nuclear envelope, rough endoplasmic reticulum, the Golgi apparatus, lysosomes, axoplasmic reticulum, and discrete cytoplasmic compartments such as vesicles, multivesicular bodies, and so on. Previous high voltage electron microscope studies of osmium-impregnated Golgi apparatus have shown that small varicose tubules often arise from the cis element. In bullfrog spinal ganglia, these tubules have been seen to extend into cytoplasmic domains occupied by rough endoplasmic reticulum (RER). This study was undertaken to determine whether varicose tubules form direct connections with RER and to measure cytoplasmic density of varicose tubules. Spinal ganglia from Rana catesbeiana were fixed by osmium impregnation and, in some cases, were then stained en bloc with lead aspartate. Sixty- to 3000-nm-thick sections of this tissue, as well as of ganglia prepared by conventional protocol, were studied using standard and high voltage electron microscopy. Quantitative analysis revealed that 9% of the varicose tubules connected with the Golgi cis element. To determine whether continuities existed between RER and any of these tubules, more than 50 tubules were fully reconstructed from images of serial sections. The "ends" of these reconstructed tubules were then studied by high magnification stereoscopy. This was facilitated by the en bloc lead staining which allowed visualization of unimpregnated RER elements along with the impregnated tubules. Small varicose tubules as well as larger smooth tubules were found to have formed confluent bridges between the cis element and RER. In addition, the varicose tubules were found to bridge widely separated elements of RER. Finally, numerous examples of varicose and smooth tubules were seen to extend from RER and from cis elements to eventually form blind endings. These findings raise the possibility that the tubules form highly dynamic transitory connections between RER and the Golgi apparatus as well as between separated elements of RER. Those between RER and Golgi apparatus are ideally positioned to play a major role in the transfer of protein or lipid components first assembled in RER to the Golgi apparatus for terminal synthetic modification.
这是三篇系列论文中的第一篇，描述了神经元内膜系统内的新组成部分和结构关系。该系统包括：核膜、粗面内质网、高尔基体、溶酶体、轴质内质网以及离散的细胞质区室，如囊泡、多泡体等。以往对锇浸染的高尔基体进行的高压电子显微镜研究表明，小的曲张小管通常起源于顺面元件。在牛蛙脊髓神经节中，已观察到这些小管延伸到粗面内质网（RER）占据的细胞质区域。本研究旨在确定曲张小管是否与RER形成直接连接，并测量曲张小管的细胞质密度。用锇浸染法固定牛蛙的脊髓神经节，在某些情况下，随后用天冬氨酸铅进行整体染色。使用标准和高压电子显微镜研究了该组织以及按常规方法制备的神经节的60至3000纳米厚的切片。定量分析显示，9%的曲张小管与高尔基体顺面元件相连。为了确定RER与这些小管中的任何一个之间是否存在连续性，从连续切片图像中对50多个小管进行了完整重建。然后通过高倍立体显微镜研究这些重建小管的“末端”。整体铅染色有助于此项研究，它使未浸染的RER元件与浸染的小管一起可视化。发现小的曲张小管以及较大的光滑小管在顺面元件和RER之间形成了融合桥。此外，还发现曲张小管在广泛分离的RER元件之间架桥。最后，观察到许多曲张小管和光滑小管的例子从RER和顺面元件延伸出来，最终形成盲端。这些发现增加了一种可能性，即这些小管在RER与高尔基体之间以及RER的分离元件之间形成高度动态的过渡连接。RER与高尔基体之间的连接处于理想位置，可在首先在RER中组装的蛋白质或脂质成分转移到高尔基体进行最终合成修饰过程中发挥主要作用。
