The aura can be in the form of prismatic colors, flashes of light, and sometimes stars. They usually last about 20 minutes and then go away. If these flashes or lines of light occur without a headache, it is called an ophthalmic migraine, or a migraine without a headache.
In gymnosperms and flowering plants, the megaspore is produced inside the nucellus of the ovule. During megasporogenesis, a diploid precursor cell, the megasporocyte or megaspore mother cell, undergoes meiosis to produce initially four haploid cells (the megaspores).
At the completion of the mitotic cell cycle, a single cell divides forming two daughter cells. A parent cell undergoing meiosis produces four daughter cells. While mitosis occurs in both prokaryotic and eukaryotic organisms, meiosis occurs in eukaryotic animal cells, plant cells, and fungi.