Fig. 6

Typical water distribution and cellular structures in konara oak (Quercus serrata) observed by cryo-scanning electron microscopy (cryo-SEM). A transverse section of annual rings from the current year, the 2nd year, and 8–9th year (innermost part of the sapwood) of a control (without Cs injection) of a normal tree (K06). Water distribution is clearly distinguished from cell walls, cell content, and tyloses (white arrows) as seen from the comparison between shallow (a–e) and deep freeze-etching (f–j) because deep freeze-etching removed sublimated ice. The boxes in a and f represent magnified images of axial parenchyma cells