Hormonal control of the menstrual cycle
The interaction of FSH, LS, oestrogen, and progesterone in the menstrual cycle
The female reproductive system includes a cycle of events called the Recurring series of events in the human female reproductive system.. It lasts about 28 days, but it can be slightly less or more than this. The cycle stops while a woman is pregnant. These are the main features of the menstrual cycle:
- The start of the cycle, day 1, is when bleeding from the vagina begins. This is caused by the loss of the lining of the Also known as a womb. This is where the fertilised egg (ovum) develops., with a little blood. This is called Also called a 'period'. The loss of blood and tissue from the lining of the uterus through the vagina during the menstrual cycle. or having a period.
- By the end of about day 5, the loss of blood stops. The lining of the uterus begins to re-grow and an egg cell starts to mature in one of the ovaries.
- At about day 14, the mature egg cell is released from the ovary. This is called The process of releasing an egg from an ovary.. The egg cell travels through the Also called a Fallopian tube or egg tube, this tube leads from an ovary to the uterus. towards the uterus.
- If the egg cell does not meet with a sperm cell in the oviduct, the lining of the uterus begins to break down and the cycle repeats.
The thickness of the uterus lining varies during the menstrual cycle. An egg is released at about day 14
The joining of a male and female gamete. happens if the egg cell meets and joins with a sperm cell in the oviduct. The fertilised egg attaches to the lining of the uterus. The woman becomes pregnant, the lining of the uterus does not break down and menstruation does not happen.
Professor Robert Winston describes the process of ovulation in humans