The post-pollination changes occur when the microspore or pollen grain falls on the stigma of pistil.
The pollen grains which are compatible absorbs water and nutrients from the stigmatic surface through germpore .
The tube or vegetative cell enlarges and comes out of the pollen grain through one of the germ pores to form a pollen tube .
The pollen tube is covered with intine and it secretes pectinases and hydrolytic enzymes which helps for the passage of pollen tube into the style.
The tube nucleus descends to the tip of the pollen tube the generative cell also passes into it and is soon divided mitotically .into two non-motile and haploid male gametes.
Each male gamete is lenticular to spherical in out line having a large nucleus which is surrounded by thin cytoplasmic sheath .One male gamete is cosidered as one cell .
Formation of male gametes may also occur prior to formation of pollentube in some cases .
This pollen grain or microspore with pollen tube carrying 2 mature male gametophyte .
Soit is 3 - celled and 3 -necleated structure .
The mature male gametophyte has 3 parts i.e. tip portion showing growth nuclear zone containing 2 male gametes and tube nucleus and vascular region at the distal end containing vacuoles and callose plugs
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