How does the process of fertilization take place in flowers?

When the pollen grain reaches the stigma of a flower, it starts giving rise to a pollen tube that passes through the style and reaches the ovary of the pistil. When the pollen tube reaches an ovule, it releases the male gametes. Male cells are released into the ovule for the fertilization with the female egg cell and thus the zygote is formed. After this process of fertilization, the ovary develops into fruit and ovule into seeds.