Fig. 6: Schematic representations of SDV-mediated and non SDV-mediated models for seta formation.
From: Structural evidence for extracellular silica formation by diatoms
a An SDV-mediated process that includes an SDV membrane surrounding the forming silica, and a dedicated cellular complex that is responsible for elongation of the seta (based on the works of J. Pickett-Heaps). Only after maturation the silica is exocytosed and become exterior to the cell membrane. b The new model based on the components identified by cryoET, with the addition of Si building blocks as small spheres, and the putative organic scaffolds that emanate from the far end of the cell cytoplasm, indicated with a red arrow. c–f Steps in the seta elongation process. A newly formed section of the organic scaffold (cyan in d–f) silicifies upon radial expansion, and then is pushed down along the seta. The organic cover was removed for clarity.
