Fig. 9
Cross sections via the single locule of Petunia anther at the pollen grain stage (Pg) show: methylene blue staining (a), immunogold localization of CRT protein (b-f) and localization of exchangeable Ca2+ by potassium antimonite precipitation (g-k). Arrow in a shows degenerating tapetum, arrows in c show CRT labeling in the chromatin associated with the nucleolus, and arrows in e show CRT labeling associated with the residual tapetum/pollen coat. ch chromatin, cy cytoplasm, er endoplasmic reticulum, ex exine, int intine, no nucleolus, Pg-gnu generative nucleus of the pollen grain, Pg-vnu vegetative nucleus of the pollen grain, Ta degenerating tapetum, v vesicle. Scale bars correspond to 25 μm (a) and 500 nm (b-k)