Light micrograph of a transverse section through the anther of a madonna lily, Lilium candidum, showing four pollen sacs filled with pollen grains (blue dots with red nuclei). Some of the pollen grains are undergoing meiosis (reduction division), the process whereby a normal diploid cell divides to form four haploid cells (gametes). Magnification: x30 at 6x4. 5cm size.