How does pollen deliver male gametes to an egg in a flowering plant?

In flowering plants, the delivery of male gametes to the egg is a precise process initiated by pollination. Once a pollen grain lands on a receptive stigma, it germinates to produce a pollen tube.123

This tube elongates and grows down through the style, nourished by secretions from the transmitting tissue. The pollen tube eventually reaches the ovule and enters through an opening called the micropyle. Upon reaching the embryo sac, the tube penetrates a specialized cell known as a synergid, where it discharges the two male gametes.21

Flowering plants undergo a unique process called double fertilization: one male gamete fuses with the egg to form a diploid zygote, while the second male gamete fuses with the polar nuclei in the central cell to form the triploid endosperm, which provides essential nutrition for the developing embryo.143