In angiosperm two fertilizations occurs in the embryo sac of the ovules. The first fusion occurs between the male nucleus and the egg cell resulting in the formation of the zygote. The second fusion occurs between second male gamete and the secondary nucleus (which in turn is formed by the fusion of the two polar nuclei) giving rise to the triploid endosperm. The endosperm nurtures the zygote and develops into the embryo. Thus the ovule becomes the seed and ovary forms the fruit.
