Fig. 5

Detailed intracellular ultrastructural features of PTs showing callose plugs, the nucleus, starch grains, and lipid bodies. ChF section through callose plugs (cp) of a PT with completely sealed off cytoplasm (a) or a plug closing in on remnant of the cytoplasm (b). The ultrastructure is more preserved in the ChF/Epon sections (a, b) than the ChF/LR white section (c). The closer view of the area marked in the LR white section showing anti-callose gold particle labelling indicated by an arrowhead (d). Sections through the nucleus (N) in ChF/Epon (e) and ChF/LR white (f). While the nuclear membrane is well resolved showing its two layers (arrow) and nuclear pores (arrowheads) in ChF/Epon section, the membrane is entirely extracted in ChF/LR white section and appears electron transparent (arrow). ChF/Epon sections show starch grains (stg) in amyloplasts (g) and a lipid body (Ld) surrounded by ribosomes (h). Lipid bodies are only clearly preserved and contrasted on ChF/Epon section. Scale bar (a–h) = 500 nm