Hormones in Reproduction

• Testosterone is the main male sex hormone and is produced in the testes. It stimulates the production of sperm and the development of male secondary sexual characteristics
• Secondary sexual characteristics are characteristics that come during puberty, such as breast development and pubic hair growth.
• Stages of the menstrual cycle

  Stage 1: Uterus lining sheds

  Stage 2: Lining of uterus builds up again

  Stage 3: Egg develops and is released from an ovary ( ovulation )

  Stage 4: Lining is maintained until day 28, where the lining breaks down and cycle restarts
• The FSH ( follicle stimulating hormone ) is produced by the pituitary gland and stimulates the ovaries to produce oestrogen. It also stimulates the maturing of the egg
• Oestrogen causes the lining of the uterus to thicken and grow. It stimulates the production of LH. It also inhibits the production of FSH to make sure only one egg is released in each cycle
• LH ( Luteinising hormone ) stimulates the release of an egg on day 14. It also indirectly triggers the release of Progesterone
• Progesterone maintains the lining of the uterus. When levels of progesterone falls, the lining sheds. Progesterone also reduces the production of FSH and LH
• Low levels of progesterone allow FSH to be reproduced, allowing the menstrual cycle to restart again
• If the egg is fertilized and the woman becomes pregnant, progesterone levels will stay high to maintain the uterus lining during pregnancy
• Ovulation is when an egg is released from the ovary
• LH stimulates follicles in the ovary to mature and one which develops the most releases an egg. The mature follicle which released the egg then becomes a corpus leteum
• The corpus luteum releases proestrogen
• The corpus luteum prepares the lining of the uterus for pregnancy by releasing some oestrogen, and the proestrogen maintains that state
• A woman is most fertile when oestrogen is at its highest level.