Electron microscopy of cellulose in entire tissue

SUMMARY Microfibrillar structures can be seen in ultrathin sections of cell walls which have been post‐stained with uranyl acetate and lead citrate. This stain is removable by washing, suggesting that a physical mechanism is involved. It is suggested that these structures are the cellulose microfibrils of the wall; they appear to be 3.5 nm in diameter and not fasciated into larger units. Freeze‐etching of untreated tissue supports this conclusion. These two techniques seem to have many advantages over methods previously used for the study of microfibril arrangement and structure.