|Figure 12. The menstrual cycle.|| |
- follicular stage, during which the follicular cells grow and divide and produce hormones, and a mature female gamete develops.
- ovulation, which is the release of the oocyte from the ovary
- luteal stage, during which the follicle cells in the ovary develop to form the corpus luteum. This structure secretes hormones which maintain the reproductive system in a condition to allow implantation and maintain pregnancy.
At the end of the luteal stage, menstruation takes place, during which the lining of the uterus is shed.
| ||As soon as antigestagens, compounds that antagonise the action of progesterone, were discovered it was clear that they would have great potential in helping to control reproduction. Chemists at Roussel-UCLAF in France synthesised the first antigestagen, mifepristone, in 1980. It was soon shown that it could be used to induce abortion. Combined with a prostaglandin, mifepristone is now licensed as a safe alternative to established surgical abortion procedures in ten European countries, including the UK, and China.|
|Using antigestagens as a contraceptive|
| ||Mifepristone has other potential uses, including contraception, but the ethical and political controversies surrounding its role in the abortion pill have impeded research. It can act as a true contraceptive by preventing ovulation. The CDN has recently been investigating whether antigestagens could be developed into an alternative to existing contraceptive pills.|
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As used by millions of women world-wide, the most popular method of contraception in the UK is the combined oral contraceptive pill. As its name implies, it is a mixture of synthetic oestrogens and progesterones which act by preventing ovulation. This type of contraception doesnt suit everyone. A few people suffer side effects due to the additional oestrogen, such as headaches and weight gain. Although the pill has an excellent safety record, there is a very slightly increased risk of complications such as blood clots in some women.