Development of the normal or Polygonum type embryo sac begins within the nucellus, as a single megasporocyte (2N) that develops and divides meiotically to produce a linear tetrad of megaspores, three of which degenerate, leaving one functional megaspore (IN). The functional megaspore enlarges and undergoes three mitotic divisions yielding eight nuclei. The nuclei are arranged in two groups of four, one group at the micropylar end of the cell and one group at the opposite end. One nucleus from each group migrates to the centre of the cell and both are referred to as polar nuclei. Cell walls form around the remaining six nuclei. At the end opposite