Sexual Reproduction in Flowering Plants

Development of male and female gametophytes

  1. Pollen grain is the first cell of male gametophyte that divides mitotically to yield a bigger tube cell (or) vegetative cell and a smaller generative cell.
  2. The tube nucleus moves to the tip of the pollen tube and degenerates where the generative cell divides into 2 male gametes.
  3. The functional megaspore is the first cell of female gametophyte (or) embryo sac, where its nucleus undergoes nuclear division (mitosis) to form 8 daughter nuclei out of which three nuclei at the base of Embryo sac form antipodal cells and other 3 at the micropylar end constitute egg apparatus, (2-synergids ; 1 – egg / oosphere) and rest 2 nucleus fuse to form a diploid (or) secondary nucleus.
  4. A filiform apparatus helps in the easy penetration of pollen tube by guiding them.
  5. Thus a typical embryo sac contains 8 nuclei but 7 celled stage (i) 3 micropylar, one central and 3 charazal.

Watch this video for the topic from 0:39 to 49:38

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