Abstract：
In humans, a quantifiable number of cortical synapses appears early in fetal life. In this paper, we present a bridge across different scales of resolution and the distribution of synapses across the transient cytoarchitectonic compartments: marginal zone (MZ), cortical plate (CP), subplate (SP), and in vivo MR images. The tissue of somatosensory cortex (7-26 postconceptional weeks (PCW)) was prepared for electron microscopy, and classified synapses with a determined subpial depth were used for creating histograms matched to the histological sections immunoreacted for synaptic markers and aligned to in vivo MR images (1.5 T) of corresponding fetal ages (maternal indication). Two time periods and laminar patterns of synaptogenesis were identified: an early and midfetal two-compartmental distribution (MZ and SP) and a late fetal three-compartmental distribution (CP synaptogenesis). During both periods, a voluminous, synapse-rich SP was visualized on the in vivo MR. Another novel finding concerns the phase of secondary expansion of the SP (13 PCW), where a quantifiable number of synapses appears in the upper SP. This lamina shows a T2 intermediate signal intensity below the low signal CP. In conclusion, the early fetal appearance of synapses shows early differentiation of putative genetic mechanisms underlying the synthesis, transport and assembly of synaptic proteins. \"Pioneering\" synapses are likely to play a morphogenetic role in constructing of fundamental circuitry architecture due to interaction between neurons. They underlie spontaneous, evoked, and resting state activity prior to ex utero experience. Synapses can also mediate genetic and environmental triggers, adversely altering the development of cortical circuitry and leading to neurodevelopmental disorders.
摘要：
在人类中,可量化数量的皮质突触出现在胎儿早期。在本文中,我们提出了一个跨越不同分辨率尺度的桥梁和跨瞬时细胞结构区室的突触分布：边缘区（MZ），皮质板（CP），子板（SP），和体内MR图像。体感皮层组织（7-26个概念后周（PCW））准备进行电子显微镜检查，和具有确定的下深度的分类突触用于创建与针对突触标志物免疫反应的组织学切片匹配的直方图，并与相应胎儿年龄的体内MR图像（1.5T）对齐（母体适应症）。确定了突触发生的两个时间段和层状模式：早期和中期胎儿两室分布（MZ和SP）和晚期胎儿三室分布（CP突触发生）。在这两个时期,大量的，富含突触的SP在体内MR上可视化。另一个新颖的发现涉及SP（13PCW）的二次膨胀阶段，其中可量化数量的突触出现在上SP中。该层显示低于低信号CP的T2中间信号强度。总之,突触的早期胎儿外观显示了合成潜在的推定遗传机制的早期分化，突触蛋白的运输和组装。由于神经元之间的相互作用，“开拓性”突触很可能在基本电路结构的构建中起形态发生作用。它们是自发的，唤起，和在子宫外经历之前的静息状态活动。突触还可以介导遗传和环境触发，不利地改变皮质电路的发育并导致神经发育障碍。
