Students should be able to explain the interactions ofFSH, oestrogen, LH and progesterone, in the control of themenstrual cycle.

The menstrual cycle is a complex process that is regulated by various hormones, including Follicle Stimulating Hormone (FSH), oestrogen, Luteinizing Hormone (LH), and progesterone. Here's a step-by-step explanation of their interactions:

1. The menstrual cycle begins with the first day of menstruation. At this point, the levels of oestrogen and progesterone are low, which signals the pituitary gland to produce FSH.

2. FSH stimulates the growth of follicles in the ovaries. These follicles contain eggs and produce oestrogen as they mature.

3. The rising levels of oestrogen in the body have two main effects. Firstly, they stimulate the growth of the uterine lining, preparing it for potential pregnancy. Secondly, high levels of oestrogen trigger the pituitary gland to produce LH.

4. The surge in LH triggers ovulation, which is the release of a mature egg from the follicle into the fallopian tube.

5. After ovulation, the follicle that released the egg transforms into a structure called the corpus luteum. The corpus luteum produces progesterone, which further prepares the uterine lining for pregnancy.

6. If the egg is not fertilized, the corpus luteum breaks down, leading to a drop in progesterone. This causes the uterine lining to shed, resulting in menstruation.

7. The drop in progesterone also removes the block on FSH production, allowing the cycle to start again.

This is a simplified explanation and the actual process involves more hormones and feedback mechanisms. However, it gives a good overview of the main roles of FSH, oestrogen, LH, and progesterone in the menstrual cycle.