Each microsporangium has inner sporogenous tissue that differentiates into microspore/pollen mother cell, they first undergo mitotic divisions to increase the cell number. The sporogenous cells are diploid and have two complete sets of chromosomes. These diploid cells undergo meiosis to produce four haploid microspores/pollen grains (B) that remain suspended in central of each microsporangium. Pollen grain is the first cell of male gametophyte wherein male gamete develops. The correct sequence is sporogenous tissue, pollen mother cell, microspore tetrad, pollen grain and male gamete.