How does a pollen tube reach an ovule in a flowering plant?

In flowering plants, the process of reaching the ovule begins when a pollen grain lands on the receptive surface of the stigma. Once deposited, the pollen grain germinates to produce a pollen tube.123

This tube elongates and grows down through the style, which is lined with secretory transmitting tissue. The secretions from this tissue provide the necessary environment to nourish the tube as it makes its way toward the base of the pistil.23

Upon reaching the ovule, the pollen tube enters through a small opening known as the micropyle. It then penetrates one of the synergids—sterile cells located on either side of the egg—where it discharges two male gametes to facilitate double fertilization.12