The formation of female gametes in an embryo sac is called : 

The process of formation of megaspores from the megaspore mother cell is called megasporogenesis. One mega spore mother cell undergoes meiosis and forms four megaspores . among four megaspores three will get degenerates and one megaspore develops as functional megaspore . functional megaspore undergoes three generations of mitosis and forms embryosac . formation of female gamete(egg) in embryosac is called as mega gametogenesis.