Pollination. Coloured scanning electron micrograph (SEM) of pollen grains (orange) on the stigmas (tips of the green projections) of a flower. Together with the ovary (not seen), which holds the eggs, and the style, the projection between the stigma and ovary, the stigma forms the female reproductive organ (pistil). Eventually, pollen tubes emerge from the grains. The pollen tubes contain the male gametes (sex cells). They grow down the style and into the ovary, where the tips of the pollen tubes rupture, releasing the gametes to fertilize the ovule (female sex cell) and produce seeds.