Pollen Development and Quantitative Cytochemistry of Exine and Intine Enzymes in Sunflower, Helianthus annuus L

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Abstract
High resolution cytochemical methods have been used to characterize pollen development and pollen-wall structure in Helianthus annuus. Aniline-blue fluorescent material, presumably callose, was detected in the nexine layer throughout its development. It was associated with acid phosphatase activity, while the outer sexine possessed intense esterase activity during the young spore period. Acid phosphatase and esterase were present in both intine and exine wall sites in contrast to their specific location in other pollen types. Quantitative cytochemical estimates of enzyme activity during development reveal esterase patterns typical of gametophytic synthesis, while acid phosphatase patterns are characteristic of sporophytic origin suggesting tapetal transfer during the vacuolate period.