The supposedly simple cycle occuring once a month is incredibly intricate and detailed, with numerous hormonal controls and checkpoints. Knobil's pelvic clock hypothesis and Derin's opioid hypothesis. I will present a digram which shows the proposed important sequence of neurons involved in the cycle and how they might be interconnected. In conclusion I will produce a summary hypothesis of what current research implies are the mechanisms of the menstrual cycle. It is necessary to begin with a basic explanation of the major events in the menstrual cycle before discussing the complex interactions bringing about such events.
Menses usually occurs for a period of five days, after which the preliferative stage begins.
Fourteen days before the onset of menses, ovulation usually occurs. LH is crucial for ovulation and subsequent increase in estrogen and progesterone secretion, while FSH is needed for preovulatory growth and development of the follicle and the concomitant follicular secretion of estrogen. During ovulation, the ovary release the egg and the corpus luteum is formed from the remaining cells. Eventually, in the absence of a fertilized egg, the corpus luteum degenerates, thus beginning the menses. . . .