Electron microscopy (EM) studies of the postmortem human brain provide a level of resolution essential for understanding brain function in both normal and disease states. However, processes associated with death can impair the cellular and organelle ultrastructural preservation required for quantitative EM studies. Although postmortem interval (PMI), the time between death and preservation of tissue, is thought to be the most influential factor of ultrastructural quality, numerous other factors may also influence tissue preservation. The goal of the present study was to assess the effects of pre- and postmortem factors on multiple components of ultrastructure in the postmortem human prefrontal cortex. Tissue samples from 30 subjects were processed using standard EM histochemistry. The primary dependent measure was number of identifiable neuronal profiles, and secondary measures included presence and/or integrity of synapses, mitochondria, and myelinated axonal fibers. Number of identifiable neuronal profiles was most strongly affected by the interaction of PMI and pH, such that short PMIs and neutral pH values predicted the best preservation. Secondary measures were largely unaffected by pre- and postmortem factors. Together, these data indicate that distinct components of the neuropil are differentially affected by PMI and pH in postmortem human brain.

中文翻译：

---

影响死后人脑前额皮质超微结构质量的因素。


对死后人类大脑的电子显微镜 (EM) 研究提供了对于了解正常和疾病状态下的大脑功能至关重要的分辨率水平。然而，与死亡相关的过程可能会损害定量电镜研究所需的细胞和细胞器超微结构的保存。尽管死后间隔（PMI），即死亡和组织保存之间的时间，被认为是超微结构质量最有影响的因素，但许多其他因素也可能影响组织保存。本研究的目的是评估死前和死后因素对死后人类前额皮质超微结构多个组成部分的影响。使用标准 EM 组织化学对 30 名受试者的组织样本进行处理。主要依赖测量是可识别的神经元特征的数量，次要测量包括突触、线粒体和有髓轴突纤维的存在和/或完整性。可识别神经元特征的数量受 PMI 和 pH 值相互作用的影响最大，因此短 PMI 和中性 pH 值预示着最佳保存。次要措施基本上不受事前和事后因素的影响。总之，这些数据表明，死后人脑中神经纤维的不同成分受到 PMI 和 pH 值的不同影响。