Formation of male gametes of gymnosperms

Question

Explain the formation of the male gametes of gymnosperms? Explain the relationship between pollen grains and concept of the alternation of generations?

Answer 1

In the male strobiles (cones) there exist microsporophylls or fertile leaves of strobile which consists of the microsporangia. Inside the microsporagium spore mother cells go through the meiosis and produce the haploid microspores. The microspore wall grows into the winglike projections (in order to facilitate its aerial propagation) and mitosis takes place generating the two cells, the generative cell and the tube cell. The final structure having these elements is the pollen grain. The pollen grain relates to the alternation of the generations as it is the male gametophyte (haploid stage of the life cycle).