In Thalassiosira pseudonana, developing silica valves form inside a silica deposition vesicle (SDV). In-cell cryo-electron tomography of vitrified cells showed opposing SDV membranes indenting toward each other at cribrum pore positions. This structural correspondence is consistent with a membrane-shaping hypothesis, but does not establish causation. Separately, images showed putative tethers between the distal SDV membrane and plasma membrane; the images alone do not directly establish contact-site function. These observations are limited to this species and the sampled valve-development stages.

Source: https://www.nature.com/articles/s41467-024-52211-x