A typical Angiosperm Embryosac is: (a) 7-nucleate, 18- celled (b) 8-nucleate , 8-celled (c) 8-nucleate, 7- celled (d)7- nucleate, 8-celled
Option C The embryo sac is formed from the megaspore mother cell by the process of megasporogenesis and mega-gametogenesis. A diploid Megaspore mother cell is developed inside the nucellus. It then undergoes meiotic division to form four haploid megaspores. This process is called megasporogenesis. Out of these four megaspores, three degenerate and only one remains functional which develops into embryo sac and this process is called megagametogenesis. This functional megaspore then undergoes mitosis three times without cytoplasmic divisions which results in 8 nuclei in the megaspore. Three of these 8 nuclei get organized into egg apparatus (consisting of an egg cell and two synergids) at the micropylar pole, two nuclei form a large central cell and three nuclei get organized in antipodal cells at the chalazal pole. This results in the formation of a 7-celled but 8-nucleate structure which is called the embryo sac.
