Pollen development in Cucumis sativus L.

Development of microspores and pollen grains of Cucumis sativus L. was stud ied at the light microscope level from meiosis to mature pollen. The first pollen mitosis occurs after microspore release from the tetrad at the vacuo late microspore stage, but this stage of development is not correlated with enlargement of the entire pollen grain; pollen grain volume grows continuo usly from microspore release until pollen dehydration, simultaneously with an increase in the amount of cytoplasm in the vegetative cell. Starch grain s in the vegetative cell appear after displacement of the generative cell i nside the pollen grain and disappear in the final stage of pollen maturatio n. Mature pollen grains are bicellular at anthesis.