An essay on the female reproductive cycle from puberty through the menstrual cycle to fertilizationFirst of all, before girls start their menstrual cycle they go through puberty, this is a process of physical, behavioral changes and psychological ones that prepare girls' bodies for childbirth and the reproductive cycle. Female puberty can be described in five different phases, the first occurring when the girl is still a child and usually lasting from eight to eleven years. The baby will have no visible changes on the outside but in his body they are producing hormones that will lead to reproductive development. Their ovaries can sometimes become enlarged due to changing hormones. The second stage is actually the beginning of puberty, this happens when the girl is between the ages of eight and fourteen, but the average is around eleven to twelve years old. Girls begin to notice physical changes such as breast buds starting to form, nipples lifting, and the areola becoming larger. Other physical changes that occur are rapid weight gain and a growth spurt where the girl will start to get taller. Pubic hair begins to grow on the labia, but is very sparse and fine. The third stage can occur from ages nine to fifteen, although it usually occurs from ages twelve to thirteen. The breasts continue to grow and become much fuller and rounder, one may grow more than the other so they may be different sizes, which is completely normal. The growth spurt continues and limbs lengthen, hips widen so the waist can appear smaller. The pubic hair becomes coarser and darker, the vagina begins to leak a fluid that may be white or light in color. The vagina also begins to widen but cannot be seen from the outside and a fifth of the paper barrier in the opening of the cervix protects the embryo that could grow in the uterus. Fertilization occurs when the sperm reaches the mature egg in the tubes of Fallopian. It generally occurs through sexual intercourse and the sperm are ejaculated into the vagina, pass through the opening of the cervix and meet the mature egg in the fallopian tubes. All it takes is one sperm to fertilize and ovulate. The sperm (male) and egg cell (female) are each called haploid cells; these are cells with a set of twenty-three chromosomes. So when the egg is fertilized with a sperm, a diploid cell is formed which is made up of the two sex cells combined, so it has two sets of twenty-three chromosomes which equals forty-six in all. Once this has occurred, the embryo can begin to develop into a baby, a cycle that usually takes nine months to complete.