Probst W
Histochemistry. 1986;85(3):231-9. doi: 10.1007/BF00494809.
The ultrastructural localization of calcium in synaptic areas of the CNS of fish was investigated. Prefixation with phosphate-buffered glutaraldehyde followed by post-fixation with osmium/potassium-bichromate was used to precipitate and visualize endogenous calcium without the addition of external calcium. The presence of calcium in the electron-dense precipitates produced using this method was demonstrated by electron spectroscopic imaging using a Zeiss EM-902 transmission electron microscope, and in various control experiments using the calcium chelator EGTA. In the optic tectum of fish, electron dense precipitates containing calcium were found not only in intracellular compartments, e.g. the smooth endoplasmic reticulum, mitochondria and synaptic vesicles, but also at extracellular locations, particularly in synaptic clefts. In the extracellular sites, only chelate complexes of ionic calcium were found. This would seem to be in agreement with electrophysiological and biochemical data reported in earlier studies. Thus, using the present method, it should be possible to obtain further ultrastructural information concerning the mechanisms of synaptic transmission.
对鱼类中枢神经系统突触区域钙的超微结构定位进行了研究。采用磷酸盐缓冲戊二醛预固定，然后用锇/重铬酸钾后固定，以沉淀和可视化内源性钙，而不添加外源钙。使用蔡司EM-902透射电子显微镜通过电子光谱成像以及使用钙螯合剂EGTA的各种对照实验，证明了使用该方法产生的电子致密沉淀物中存在钙。在鱼的视顶盖中，不仅在细胞内区室，如光滑内质网、线粒体和突触小泡中发现了含钙的电子致密沉淀物，而且在细胞外位置，特别是在突触间隙中也发现了。在细胞外部位，仅发现了离子钙的螯合物。这似乎与早期研究报道的电生理和生化数据一致。因此，使用本方法应该有可能获得关于突触传递机制的进一步超微结构信息。
