Explanation

Nucellus Integuments encloses a mass of cells called nucellus. Cells of the nucellus have abundant reserve food materials. Located in the nucellus is the embryo sac or female gametophyte. An ovule generally has single embryo sac formed from a megaspore through reductional (meiotic) division [image:2_image57.png] (a) Parts of the ovule showing a large megaspore mother cell, a dyad and a tetrad of megaspore (b) 2, 4 and 8-nucleate stages of embryo sac and a nature embryo sac (c) A diagrammatic representation of the mature embryo sac