Formation of female gametes, Biology

Formation of female gametes:

  1. Ovule develops from a cushion like part of the ovary called the PLACENTA. Ovule is connected to the placenta by a stalk known as FUNICLE.
  2. The tissue enclosed inside the ovule is NUCELLUS. It is surrounded by two coverings or INTEGUMENTS which leave a small pore known as MICROPYLE.
  3. Basal part of ovule where the two integuments arise is known as CHALAZA.
  4. From the cells of the nucellus, one cell differentiates as MEGASPORE MOTHER CELL which is diploid (2n).
  5. The megaspore mother cell divides by meiosis to form four megaspores out of which only one develops as embryo sac. This is haploid and is also called Female Gametophyte.
  6. At the time of fertilisation there will be a total of 7 cells arranged in three groups in a mature embryo sac.
  7. They are one egg, two synergids, one central cell three antipodals.
  8. While all the cell are in haploid condition only the secondary nucleus is diploid.
Posted Date: 8/29/2012 6:20:15 AM | Location : United States







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