TO STUDY THE POLLEN TUBE GROWTH IN STIGMA

In this video we will see the Pollen germination which starts with the pollen grain landing on stigma. The pollen grain is uninucleate (has one nucleus) in the beginning. At the time of liberation, it becomes 2 celled, one of these is smaller in size and called generative cell and bigger one is called tube cell.
In the nutrient medium, the pollen grain germinates. The tube cell enlarges and comes out of the pollen grain through one of the germ pores to form a pollen tube.  The tube nucleus descends to the tip of the pollen tube. The generative cell also passes into it. It soon divides into two male gametes. This pollen tube bursts open and the male gametes are released -one of which then fuse with the egg cell and other nuclei with two polar nuclei.