Electron microscopy (EM) provides the necessary resolution to visualize the finer structures of nervous tissue morphology, which is important to understand healthy and pathological conditions in the brain. However, for the interpretation of the micrographs the tissue preservation is crucial. The quality of the tissue structure is mostly influenced by the post mortem interval (PMI), the time of death until the preservation of the tissue. Therefore, the aim of this study was to optimize the preparation-procedure for the human frontal lobe to preserve the ultrastructure as well as possible despite the long PMIs. Combining chemical pre- and post-fixation with cryo-fixation and cryo-substitution ("hybrid freezing"), it was possible to improve the preservation of the neuronal profiles of human brain samples compared to the "standard" epoxy resin embedding method. In conclusion short PMIs are generally desirable but up to a PMI of 16 h the ultrastructure can be preserved on an acceptable level with a high contrast using the "hybrid freezing" protocol described here.

中文翻译：

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长时间死后间隔后透射电子显微镜对人脑超微结构保存的优化。

电子显微镜 (EM) 提供了必要的分辨率来可视化神经组织形态的更精细结构，这对于了解大脑中的健康和病理状况非常重要。然而，对于显微照片的解释，组织保存是至关重要的。组织结构的质量主要受死后间隔 (PMI) 的影响，即死亡时间直到组织保存。因此，本研究的目的是优化人类额叶的制备程序，以尽可能地保留超微结构，尽管 PMI 很长。将化学预固定和后固定与冷冻固定和冷冻替代（“混合冷冻”）相结合，与“标准”相比，可以改善人脑样本神经元轮廓的保存 环氧树脂包埋法。总之，短 PMI 通常是可取的，但在 16 小时的 PMI 内，使用此处描述的“混合冷冻”协议，超微结构可以保持在可接受的水平，并具有高对比度。