Question
Embryo sac.

Answer

  1. Egg apparatus is a three celled structure lying at the micropylar end of the embryo sac.
  2. The egg apparatus consists of a median egg cell called oosphere and two lateral cells called synergids.
  3. The embryo sac also consists of three antipodal cells or antipodals towards the chalazal end which degenerate after fertilization.
  4. In the centre, the embryo sac consists of a large central cell consisting of two haploid polar nuclei.
  5. The polar nuclei at a later stage fuse with each other forming a diploid secondary nucleus.
  6. The secondary nucleus develops into endosperm.

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