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Development of Female Gametophyte Short Note class 12


Describe the development of female gametophyte of  angiosperms?(5 mark)


Ans-The process of development of female gametophyte or embryo sac from megaspore is called megagametogenesis.

      The megaspore is the first cell of the female gametophyte.The process of formation of megaspore from the megaspore mother cell is called megasporogenesis.
Development of female gametophyte:-
i) The functional megaspore is the first cell of female gametophyte.

ii) The nucleus of the megaspore divide mitotically to form eight nuclei.

iii) Generally four nuclei are seen at the micropylar end and other four,seen at chalazal end of the enlarged megaspore.

iv) One nucleus from each end migrate to the centre of embryo sac and form polar nuclei.

v) The three cell at the micropylar end form egg apparatus and those at chalazal end form antipodal cells.



Structure of female gametophyte:-


  • The female gametophyte is a 7 celled and 8 nucleotide structure.

  • The middle cell of egg apparatus called egg cell  and two laterally placed cells are called synergies

  • Polar nuclei situated in the centre of the embryo sac.
The antipodal cells at chalazal end are degenerate soon after fertilization.

Conclusion:-

  • After formation of female gametophyte,fertilization may take place in favourable condition in angiospermic plant it is double fertilization and triple fusion.
  • After fertilization the egg cell develop into embryo and polar nuclei develop into endosperm.

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