Explain the process of Microgametogenesis.

A newly formed pollen grain possesses a very dense cytoplasm with a central nucleus. As the cell increases in size, the vacuole develops and the nucleus is shifted at the side adjacent to the wall. The nucleus divided into two smaller generative towards the wall and a larger vegetative nucleus towards the center. After the generative nucleus divided into the nucleus stage. These are called sperm nuclei male gametes. At the three celled stages normally on stigma the exine of pollen grain rupture at the germ pore and the intine in squeezed out with its content. A tube-like structure is formed called a pollen tube. The tube nucleus enters into the pollen tube and two male gametes follow the tube nucleus. As pollen tube contains the enzymes like analysis, invertase, phosphatase, pectinase, lipase, etc. It can degrade the chemical contained in style and grows towards the ovary. In this way, a mature male gametophyte contains a pollen tube with a tube nucleus and two males gametes.