Essential Parts of Flower: Androecium - Development of Male Gametophyte

Development of Male gametophyte:

• The microspore is the first cell of the male gametophyte and is haploid.
• The development of male gametophytes takes place while they are still in the microsporangium.
• The nucleus of the microspore divides mitotically to form a vegetative and a generative nucleus.
• A wall is laid around the generative nucleus resulting in the formation of two unequal cells, a large irregular nucleus bearing with abundant food reserve called a vegetative cell and a small generative cell.
• Generally, at this 2 celled stage, the pollens are liberated from the anther.
• In some plants, the generative cell again undergoes a division to form two male gametes.
• In 60% of the angiosperms, pollen is liberated in 2 celled stages. Further, the growth of the male gametophyte occurs only if the pollen reaches the right stigma. The pollen on reaching the stigma absorbs moisture and swells.
• The intine grows as a pollen tube through the germ pore.
• In case the pollen is liberated at 2 celled stages the generative cell divides in the pollen into 2 male cells (sperms) after reaching the stigma or in the pollen tube before reaching the embryo sac. 
  

  Development of male gametophyte