Figure 6.

(top panel). 3D visualization of one crescent-shaped NOR. The tomographic reconstruction of the NOR showed in Figure 5H is used for 3D visualization. (A) Overall 3D visualization of one crescent-shaped NOR. (B) The previous image is colored and labeled to describe the organization of the NOR more easily. Three regions are identified along the cord of the NOR 150–300 nm in diameter. Regions I and II are two coils with an external and internal diameter of 765 nm and 360 nm, respectively. Region III is prominent and corresponds to a central position where the two coils are apposed. Note that arrowheads 1 and 2 correspond to two angles of view shown in C, G, and E, respectively. (C) Stereo pair (to be observed with a stereo viewer to discern the 3D organization) demonstrating the curved shape of the region II and its flattened distal extremity (angle of view 1 on B). A fiber 60–80 nm in diameter appears on the proximal part of region III and on the distal part of region II (D, arrows 1 and 2). Bar, 100 nm. (E–H) Close-up views of the 60- to 80-nm fiber visualized with a higher threshold. (E and F) Within the crescent-shaped NOR observed at the level of the region II (B, angle of view 2). (G and H) Within the region I (B, angle of view 1). (E) Stereo pair demonstrating the helical organization of the fiber. (F) Size a is 80 nm in this view. (G) Stereo pair with a high depth of field showing the presence of numerous regularly arranged loops of the fiber both in front and rear planes. (H) The size of the fiber b is 60 nm; size c is 260 nm. Bar, 100 nm.