• During puberty reproductive hormones cause secondary sex characteristics to develop.
• Oestrogen is the main female reproductive hormone produced in the ovary. At puberty eggs begin to mature and one is released approximately every 28 days. This is called ovulation.
• Testosterone is the main male reproductive hormone produced by the testes and it stimulates sperm production.
• Several hormones are involved in the menstrual cycle of a woman.
• The menstrual cycle is a cycle of physiological changes that take place in women only a monthly basis. It is more commonly known as a period.

Key Stages

1. High levels of FSH will stimulate the egg to be ripe in the ovaries
2. Oestrogen then stimulates the womb lining to build up so that the woman can be prepared if an embryo does grow inside of her.
3. At around day 14, LH stimulates the release of the egg.
4. Progesterone would maintain the uterus lining.
5. Low levels of oestrogen and progesterone will cause the uterus lining to break down.
6. As a result, blood and tissue will be loss – this is called menstruation.

Hormone Interaction

The hormones interact during the menstrual cycle in order for the cycle to take place.

• High levels of FSH stimulates the ovaries to produce oestrogen.
• When oestrogen is produced, it stops FSH production.
• This then causes LH to be produced – and this leads to ovulation on day 14.
• Meanwhile, progesterone levels will increase as it is created by the follicle.
• After day 14, progesterone continues to be released as it stops the lining from breaking down, as well as prevent another egg from being released.
• If a woman is not pregnant, the egg will degenerate with the lining of the womb. Progesterone levels will then drop and menstruation occurs.