MEGASPOROGENESIS:
Definition: The process of formation of megaspores from megaspore mother cell (MMC) is called megasporogenesis.
i) Embryosac generally develop from a single megaspore that differentiate from a single megaspore mother cell (MMC) in the micropylar region of the nucellus.
ii) MMC is a large cell containing dense cytoplasm and a prominent nucleus.
iii) The MMC undergoes meiosis and forms a linear tetrad of four haploid megaspores. Out of which one remains functional (chalazal end) and three degenerate (micropylar end).