Question

pollen grain are formed by ----- ----- ----- division in locules of anthers

Answer 1

meotic division.......

Answer 2

Both mitosis and meiosis take place in the formation of pollen grains.

Pollen grain formation take place in two pollen sacs located in the anther.In each chamber micro spore mother cells undergoes meiosis and results in 4 haploid micro spores. Then each micro spore under goes mitosis and develop into pollen grains. Normally,  one micro spore develops and the rest of the 3 degenerates.