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).
DNA replication occurs during the S stage of interphase. Interphase is the stage between two mitotic or meiotic divisions. It can be slpit into three stages:G1, S and G2. During G1 (gap 1), cells grow and build up ATP on preparation for DNA replication. During the S (synthesis) phase the DNA is replicated. During the G2 phase the cell prepares itself for the process of cell division (mitosis or meiosis). See: http://www.emc.maricopa ....