A menstruation cycle usually has 4 phrases. around 28 days, or a month. menstruation, repair phrase, receptive phrase, and premenstrual phrase. between repair phrase and receptive phrase, an ovum is release from an ovary. that usually occurs during the 13th to 15th day of the cycle. therefore, AROUND the first 12 days should not be any eggs. note that each women has different cycle lengths and each cycle may be different.
Limiting factors, such as carrying capacity, competition between species, natural resources, food, shelter, water, adaptation to the environment, etc.
The same is true for our skin and our liver cells. Or our brain and muscle cells. Or any of the other 300 or so different cell types. These cells are different because they use the same set of genes differently.
The energy change in a chemical reaction is due to the difference in the amounts of stored chemical energy between the products and the reactants. This stored chemical energy, or heat content, of the system is known as its enthalpy.