Pollen, anther, tube nucleus and pungamete of plants are collectively called pungametophyte. The anthers of plant stamens contain pollen mother cells. Each pollen mother cell produces four microspores or pollen grains by meiosis. Pollen is the first cell of the male gametophyte. Its nucleus divides to form two nuclei. The larger one is called the tubular nucleus and the smaller one is called the gonial nucleus. The ductal nucleus is round and the gonial nucleus is slightly curved. In this condition, the anther wall ruptures and binucleate pollen grains come out. Through pollination, it falls into the ovary of the female flower. When the pollen comes in contact with the endosperm, it gets stuck in the sticky sap and swells by absorbing the endosperm sap. Swelling causes pressure inside the pollen tube. The pressure causes the inteins to come out of the tube through the pore. It is called pollen tube. The process of pollen tube formation is called pollen emergence or germination. Cutinase enzyme degrades the cutin of the endosperm and the pollen tube enters the endosperm. The tube nucleus enters the pollen tube first and the generative nucleus later. The pollen tube enlarges and moves towards the ovary. Before the ovum reaches the pore, the germinal nucleus divides to produce two gametes or spermatozoa. The development of the pungametophyte is complete with the production of spermatozoa.