Question

With the help of suitable diagrams trace the growth of pollen tube right from the deposition of pollen grain on the stigma up to fertilization.

Answer 1

A pollen tube is a tubular structure produced by the male gametophyte of seed plants when it germinates. Pollen grains take up water and other compounds provided by stigma papillae. Due to the swelling of pollen grains, the pores or slits – that the germinating places of the pollen tube – are exposed, and pollen germination can start. The intine layer protrudes and the pollen tube grows onto the surface of the stigma. The pollen tube enters the tissue of stigma and grows downward in the intercellular space or loose walls of the transmission tissue. Reaching the end of the style, pollen tubes enter into the ovary and continue their way on the inner surface of the ovary or on the central axis where fertilization process takes place.