Fig. 6: Organic structures associated with silica formation.

A A recurring feature in at least ten cryoET datasets is a bundle of filaments external to the expanding SDV. An orange arrowhead in the image and orange fibers in the surface representation. See also Supplementary Fig. S12. B High magnification cryoET slices of the forming silica. At the initial stages, the pores appear empty (black arrowheads), but at a later stage of silica formation, an electron-dense structure blocks the center of the pores (light blue arrowheads), and a thin layer is covering the entire silica (white arrowheads). C A representative cryoTEM image of an extracted valve SDV representing two independent experiments. The inset shows one of the cribrum pores in higher magnification. Scale bars are 50 nm and 10 nm for the inset in (C).