The menstrual cycle is the fluctuation in hormonal levels in human females and the series of physiological changes that accompany them. The menstrual cycle has arbitrarily been set to begin on day 1. Day of menstruation, noticeable loss of tissue through vagina. One of the key things to notice in this cycle is that spike of leutenizing hormone. We"re going to explore the build-up to the point and what happens after. Named follicular phase because follicles are going to start developing. Degeneration of uterine endometrium because of low estrogen and progesterone levels. Secretion of fsh and lh is low to moderate. The presence of fsh causes a continuous and steady development of several follicles. Day 7-8: dominant follicle selected and produces estrogen. On day 7 or 8, one of the follicles becomes dominant and starts to produce more estrodiol. Under influence of estrogen, endometrium begins to grow thicker. And begin positive feedback loop to anterior and posterior pituitary gland.