Cones contain the reproductive organs of gymnosperms. Male pollen cones contain pollen (which produce sperm), while female ovulate cones contain the egg. Upon pollination, a pollen tube extends from the pollen grain towards the archegonium which contains the egg. As the sperm and egg mature, the sperm's nucleus undergoes further division to produce two sperm cells. When the nuclei of the sperm come into contact with the egg cell, one nucleus dies while the other nucleus fuses with the egg cell, forming a diploid zygote. When the zygote undergoes mitosis, a new sporophyte generation (in the form of a seed embryo) is formed.