The megapinosome is an endocytic cell organel that we observed in human macrophages with electron microscopy. In a previous work we showed that it is formed by an endocytic event that we called megapinocytosis. The megapinosome is filled with a membrane surrounded trabecular meshwork that is topologically part of the cytosol. In this work we used scanning transmission electron tomography on high pressure frozen and freeze substituted human macrophages in order to unravel the three-dimensional structure of both the megapinosome and the adjacent structures. The megapinosome consists of the trabecular meshwork and the lacunae which are connected with and topologically equivalent to the cytosol. The surrounding lumen is topologically equivalent to the structures of the vesicular pathway. In addition, we show the connections of the trabecular meshwork with the cytosol and the connection of the megapinosomes to a complex tubular and cisternal system covering a large part of the macrophages that we named megapinosome complex. We assume that our methodological approach, based on high pressure freezing from a defined physiological state and three-dimensional imaging, renders the tubular components of the macrophages better visible than the classical two-dimensional imaging of chemically fixed cells used as a "blueprint" for textbook illustrations. The cell biological functions of the megapinosome are largely enigmatic. Probably, megapinosomes assures storage of surface membranes that can be promptly made available when a macrophage needs to change shape to move through a tissue, to uptake extracellular material or dead cells as well as to fight against microbes.

中文翻译：

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Megapinosome：新型细胞器的形态描述。

megapinosome是我们在人类巨噬细胞中通过电子显微镜观察到的内吞性细胞器。在以前的工作中，我们证明了它是由称为“巨胞饮”的内吞事件形成的。巨蛋白体充满了围绕小梁网的膜，该膜是细胞溶胶的拓扑结构的一部分。在这项工作中，我们对高压冷冻和冷冻替代的人类巨噬细胞使用了扫描透射电子层析成像技术，以揭示巨胞体和邻近结构的三维结构。巨细胞体由小梁网和腔隙组成，它们与胞质溶胶连接并在拓扑学上等效。周围的管腔在拓扑学上等同于囊泡通路的结构。此外，我们显示了小梁网与胞质溶胶的连接以及巨细胞体与复杂的管状和脑池系统的连接，该系统覆盖了我们称为巨细胞体复合物的巨噬细胞的很大一部分。我们假设我们的方法学方法基于已定义的生理状态的高压冷冻和三维成像，使得巨噬细胞的管状成分比传统的化学固定细胞的二维二维成像（用作“蓝图”）更好地可见。教科书插图。大骨架的细胞生物学功能在很大程度上是莫名其妙的。巨噬细胞可能会确保表面膜的储存，当巨噬细胞需要改变形状以在组织中移动时，这些膜可立即提供。