Production of microspore and megaspore is known as Sporogenesis. Microspore i.e pollen grains are produced in anther, while megaspore produced in ovules.
Each anther has four pollen sac and each pollen sac contains numerous pollen mother cells (P.M.C) which undergoes meiosis. i.e two meiotic division to produce four haploid cells or microspore. This process is known as micro-Sporogenesis. The microspores mature into pollen grains mainly by thickening of their walls.
It occurs in ovule, which are present in ovary. A single cell in each ovule differentials into Megaspore mother cell ( M.M.C). Each megaspore mother cell undergoes meiosis to produced four haploid megaspore. Out of these three- megaspore degenerate and only one functional megaspore is remaining per ovule.