Figure 6. Spatial relationship between chloroplast envelope inner membrane invaginations and thylakoid tips.
(A and C) Slices from tomographic volumes and (B and D) corresponding 3D segmentations showing thylakoid membranes (dark green), thylakoid lumina (light green), and the chloroplast envelope (blue). Inner membrane invaginations (arrows) are frequently found in close proximity to the tips of thylakoid sheets. (E–G) Three sequential slices through a tomogram and (H) corresponding 3D segmentation, where a region of thylakoid tip (∼25 nm high and ∼20 nm wide) is connected to the chloroplast envelope inner membrane. The tomograms were 2× binned. Unbinned pixel size: 5.7 Å. Segmented tomogram thickness: 137 nm in B, 135 nm in D, 69 nm in H. Scale bar: 100 nm.