Without any chemical fixation, which would be detrimental for dried microstructures, SEM enables to view the inside structure of dry seeds. Here we studied dry seeds, both from the outside, and freeze-fractured in various orientations.

We found that the dry seeds contain a continuous network of intercellular spaces. The finding that intercellular spaces are so dispersed and also interconnected gives reason to suppose that upon imbibition the moist air can move through the seed fairly quickly, thereby causing pre-wetting before liquid water enters the seed. This is important for the gradual rehydration of the cell membranes, which otherwise would collapse (imbibition damage). The hypothesis that a continuous network of intercellular spaces is present throughout the seed has not been fully proven with this research, but it has been made plausible. Follow-up question is how intercellular space networks are present in different tissues and whether this is different for other plant species. Since many dry seeds contain liquid oil, it is recommended to study dry seeds with cryo-SEM, to ensure physical fixation of oil into the solid state.