This 3D animation explains the hormonal changes during the menstrual cycle. The menstrual cycle begins with menstrual bleeding, marking the follicular phase’s first day. When the follicular phase begins, levels of estrogen and progesterone are low. As a result, the top layers of the uterus’s thickened lining break down and are shed, and menstrual bleeding occurs. About this time, the pituitary gland starts sending follicle-stimulating hormone to your ovaries, stimulating the development of 5 to 20 follicles in the ovaries. Each follicle contains an immature egg and produces estrogen. One follicle will soon begin to grow faster than others. This is called the dominant follicle. As the follicle grows, the levels of estrogen in the blood rise significantly. This increase in estrogen begins to inhibit the secretion of the follicle-stimulating hormone. The fall in follicle-stimulating hormone allows smaller follicles to die off. They are, in effect, "starved" of follicle-stimulating hormone. The increasing amount of estrogen in your body also ensures that the lining of your womb thickens with nutrients and blood. This is so that if you do get pregnant, the fertilized egg will have everything it needs to grow. The ovulatory phase begins with a rise in the levels of luteinizing hormone and follicle-stimulating hormone. The surge in the luteinizing hormone triggers one of the most prominent follicles to pop open and release its egg, which heads into the fallopian tube and starts its journey toward the uterus. Ovulation usually occurs 16 to 32 hours after the beginning of the surge, around day 14 of the menstrual cycle. During the luteal phase, the levels of the luteinizing hormone and follicle-stimulating hormone decrease. The ruptured follicle closes after releasing the egg and forms a corpus luteum, which produces estrogen and progesterone, which cause the lining of the uterus to thicken even more. If an egg is fertilized, progesterone supports early pregnancy. But if no fertilization occurs, the corpus luteum will break down between 9 and 11 days after ovulation. This results in a drop in estrogen and progesterone levels, bringing us back to the first stage of menstruation if no pregnancy has occurred. Timecodes: 0:00 Menstrual Bleeding 0:07 Follicular Phase 0:36 Dominant Follicle 1:12 Ovulation 1:37 Luteal Phase 1:46 Corpus Luteum 0:54 Implantation 1:04 Next video #Menstruation #Menstrualcycle #animation