FIGURE 1: “Thick” and “thin” TNT connections. Cryo-electron microscopy shows that TNTs can either be a single thick connection or a bundle of thin individual TNTs (iTNTs). Both open-ended and closed-ended protrusions can be present within a bundle. Each iTNT contain actin bundles, can contain vesicles and mitochondria. Thin and short membrane threads connect several iTNTs, which appear to grow in opposite directions. Adapted from Sartori-Rupp et al. [31].