Sexual Reproduction in Flowering Plants
Development of male and female gametophytes
- 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.
- The tube nucleus moves to the tip of the pollen tube and degenerates where the generative cell divides into 2 male gametes.
- 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.
- A filiform apparatus helps in the easy penetration of pollen tube by guiding them.
- 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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