Question

Explain the development of a pollen grain in the anther.

Answer 1

1. Each anther lobe contains two microsporangia. Their walls enclose sporogenous tissue, whose cells develop into diploid pollen mother cells.
2. Each pollen mother cell undergoes meiosis and forms four haploid microspores arranged in a tetrad; this is microsporogenesis.
3. The microspores separate and mature into pollen grains. Each develops an outer exine containing resistant sporopollenin and an inner cellulose-and-pectin intine.
4. The microspore nucleus divides mitotically to form a large vegetative cell and a smaller generative cell. The generative cell may divide to form two male gametes before pollen release or later in the pollen tube.
5. The tapetum nourishes developing pollen. At maturity, the anther dries and dehisces, releasing the pollen grains.