Female Gametophyte or Megasporogenesis
The pistils are the female reprocutive organs called as megasporophyll in the flowering plants. The ovary of the carpel contains ovules (megasporangia). Each
Ovule consists of megasporophytes or megaspore mother cells (MMC). Each megaspore mother cell undergoes meiosis and produces four haploid megaspores arranged in the linear row. Out of four megaspores, three degenrrates and one remains functional. This process of development of megaspores is known as megasporogenesis.
The functional megaspore divides three times mitotically giving rise to eight nucleate structure called female gametophyte or embryo sac. One nucleus from each end passes to the centre to form polar nuclei. The three nuclei at micropylar region are organised into three cells forming egg apparatus. One of the largest called egg cell or female gamete. The other two cells called synergids or helpers. The three nuclei at chalazal end (region) are organised into three cells called antipodal cells. By this way embryo sac is developed.