Multi image tiling of the trophosome area of Paracatenula sp. santandrea

Five specimen of Paracatenula sp. santandrea were fixed with PHEM buffered glutaraldehyde as described by Montanaro et al. (doi: 10.7717/peerj.1860 ) and processed with a high pressure freezer. Samples freeze-substituted in acetone with 1% w/v osmium tetroxide as described by McDonald and Webb (doi:10.1111/j.1365-2818.2011.03526.x ). All samples were embedded in Low Viscosity Resin using centrifugation embedding as described by McDonald (doi: 10.1017/S1431927613013846 ) and ultrathing sections were cut, mounted on slot grids, contrasted with lead citrate and uranyl acetate and then imaged with a Quanta FEG 250 scanning electron microscope equipped with a STEM detector. Images were recorded with a 10-20% overlap to allow reassembly with imaging software afterwards. Each image stack represents one sample.

五份Paracatenula sp. santandrea标本采用PHEM缓冲戊二醛进行固定，具体操作参照Montanaro等人的研究（doi: 10.7717/peerj.1860），随后通过高压冷冻仪完成前处理。
样本以丙酮为溶剂，添加1%质量体积比的四氧化锇进行冷冻替代，具体步骤参照McDonald与Webb的研究（doi:10.1111/j.1365-2818.2011.03526.x）。
所有样本均采用离心包埋法包埋于低黏度树脂（Low Viscosity Resin）中，具体方法参照McDonald的研究（doi: 10.1017/S1431927613013846）；随后制备超薄切片（ultrathin section），将其粘贴于狭缝载网之上，使用柠檬酸铅与醋酸铀酰进行染色，最后搭载STEM探测器（STEM detector）的Quanta FEG 250型扫描电子显微镜完成成像。
成像时设置10%~20%的图像重叠率，以便后续借助成像软件完成图像拼接；每一组图像栈对应一份样本。