Sex Hormones and Immune Dimorphism

Figure 3

The menstrual cycle has 2 phases, namely, follicular phase and the luteal phase. The follicular phase starts at the beginning of menstruation. Follicle stimulating hormone (FSH) rises and stimulates follicular growth. The 17 beta-estradiol produced by the follicles inhibits FSH. 17 beta-estradiol continues to rise due to the growing dominant follicle and high concentrations of this hormone trigger the production of luteinizing hormone (LH) by the pituitary. LH then induces ovulation. After ovulation, the luteal phase starts. The remainder of the follicle develops into the corpus luteum, which starts producing progesterone and 17 beta-estradiol. If pregnancy does not occur, progesterone and 17 beta-estradiol concentrations decrease, menstruation starts, and a new cycle can begin [50].