| The development of anthers and pollen grains of Brassica napus is examined, in particular the vacuole and its contents within pollen grains. Anther development is similar to most angiosperms except for the presence of epidermal 'motor' cells which may contribute to pollen dispersal. Vital staining with Toluidine blue O reveals that the large central vacuole in the live grains breaks up into small vesicles around the first mitosis. Vital staining, chromatography of extracts of these grains, and analyses of the specificity of Toluidine blue O for various purified compounds, suggest that these vesicles accumulate phenolic compounds, possibly flavonoids. In fixed and sectioned pollen grains there is a sudden occurrence of heavy cytoplasmic staining and poor nuclear staining which coincides with the onset of accumulation of phenolic compounds within the vesicles. Treatment of pollen grains and other 'model' plant cells with conventional chemical fixatives and freeze substitution procedures suggests that this is an artifact probably caused by mordanting of released vacuole compounds throughout the cell. |
