(a) A 7 × 7 2D mosaic collected with reference applied and background subtracted. (b) A single projection of the area boxed blue in (a) during tilt series data acquisition. (c) A slice of a reconstructed 3D tomogram of the same area in (b), showing a junction between two cells. Scale bars: (a) 10 µm (b) and (c) 1 µm. Arrows are pointing at different cellular components: green- endoplasmic reticulum, yellow- mitochondria, blue- cristae, red- nuclear envelope, purple- lipid droplets, orange- cell membrane. Cyt = cytoplasm, Nu = nucleus. Image courtesy of Dr Nina Vyas (Diamond Light Source, U.K.).