Puberty and Menstrual Cycle

• Puberty is the period during which adolescents start to develop secondary sexual characteristics, such as facial hair in men and breasts in women, triggered by reproductive hormones.
• The reproductive hormones include testosterone in men, produced in the testes and stimulating sperm production, and estrogen in women, produced by the ovaries.
• The menstrual cycle involves four stages: menstruation, when the uterus lining breaks down and bleeds for about four days; the build-up stage, when the uterus lining starts to build up and becomes a thick spongy layer with lots of blood vessels in it, lasting around ten days up to day 14; ovulation, when the egg is released from one of the ovaries, lasting a single day; and the maintenance stage, which stretches from day 14 to the end of the cycle, maintaining the lining of the uterus.
• The average length of a menstrual cycle is around 28 days but it varies a lot between different people and that's perfectly healthy.
• The hormones responsible for the menstrual cycle include estrogen, produced in the ovaries and stimulating the uterus lining to grow, progesterone, produced in the ovaries and maintaining the lining of the uterus, luteinizing hormone LH, produced in the pituitary gland and stimulating the release of an egg, and follicle stimulating hormone FSH, also produced in the pituitary gland and stimulating the maturation of an egg.
• FSH stimulates the ovaries to produce estrogen, which is why we see higher levels of FSH just before estrogen starts to increase, and when estrogen levels get high, FSH inhibits its own release, causing an LH spike and resulting in ovulation.
• Progesterone inhibits both LH and FSH, causing the menstrual cycle to stop if no fertilized egg has made it to the uterus.