Ptychographic hard X-ray computed tomography (PXCT) is a recent method allowing imaging with quantitative electron-density contrast. Here, we imaged, at cryogenic temperature and without sectioning, cellular and subcellular structures of a chemically fixed and stained wild-type mouse retina, including axons and synapses, with complete isotropic 3D information over tens of microns. Comparison with tomograms of degenerative retina from a mouse model of retinitis pigmentosa illustrates the potential of this method for analyzing disease processes like neurodegeneration at sub-200 nm resolution. As a non-destructive imaging method, PXCT is very suitable for correlative imaging. Within the outer plexiform layer containing the photoreceptor synapses, we identified somatic synapses. We used a small region inside the X-ray-imaged sample for further high-resolution focused ion beam/scanning electron microscope tomography. The subcellular structures of synapses obtained with the X-ray technique matched the electron microscopy data, demonstrating that PXCT is a powerful scanning method for tissue volumes of more than 60 cells and sensitive enough for identification of regions as small as 200 nm, which remain available for further structural and biochemical investigations.

中文翻译：

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使用 ptychographic 硬 X 射线断层扫描对视网膜细胞和亚细胞结构进行成像。

Ptychographic 硬 X 射线计算机断层扫描 (PXCT) 是一种允许使用定量电子密度对比度成像的最新方法。在这里，我们在低温下对化学固定和染色的野生型小鼠视网膜的细胞和亚细胞结构进行了成像，包括轴突和突触，具有超过数十微米的完整各向同性 3D 信息。与来自视网膜色素变性小鼠模型的退行性视网膜断层图的比较说明了这种方法在分析疾病过程（如亚 200 nm 分辨率下的神经变性）方面的潜力。作为一种无损成像方法，PXCT非常适用于相关成像。在包含光感受器突触的外丛状层内，我们确定了体细胞突触。我们使用 X 射线成像样本内的一个小区域进行进一步的高分辨率聚焦离子束/扫描电子显微镜断层扫描。使用 X 射线技术获得的突触亚细胞结构与电子显微镜数据相匹配，表明 PXCT 是一种强大的扫描方法，可用于超过 60 个细胞的组织体积，并且足够灵敏，可以识别小至 200 nm 的区域，这些区域仍然可用用于进一步的结构和生化研究。