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).
Mitosis occurs only in eukaryotic cells and the process varies in different organisms. For example, animals undergo an open mitosis, where the nuclear envelope breaks down before the chromosomes separate, while fungi undergo a closed mitosis, where chromosomes divide within an intact cell nucleus.he process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next.