Also known as oogenesis, oocyte development (the female reproductive cells) spread over several years, from foetal life to adulthood. In mammals, females are born with a stock set of oocytes which decreases with age. This explains the limited duration and the gradual decline of fertility in women.Since studies in mice in 2004, there is a new theory called neo-oogenesis, by which it would be possible to renew an artificial part of the stock of oocytes, using stem cells. However to date there is no certainty about the neo-oogenesis, because of controversy surrounding the studies which led to the concept.Treatments of infertility (including IVF or in vitro fertilization) are based on knowledge of oogenesis and ovarian physiology.
Ovarian reserve::
definition
It is the number and amount of oocytes present in primordial follicles located in the ovaries at any given time. The more the ovarian reserve is high the better the chances of conception (spontaneous or assisted) and ovarian response to hormonal stimulation before possible fertilization.This reserve is the stock of oocytes that can still be fertilized, thus indicating the remaining time for the best chance of results.
Ovarian reserve can be measured by indirect means: :
- the biological measurement of serum- FSH (follicle stimulating hormone) and estradiol: This hormonal balance test is carried out on the third day of the menstrual cycle. Elevated markers above a certain threshold means that there is ovarian failure. However, these markers are a more reliable prognosis of IVF than for the prognosis of stimulation.- AMH (Anti-Müllerian Hormone): This hormone is a marker of ongoing assessment to measure ovarian reserve. The AMH is the best marker of ovarian response to hormonal stimulation because: :it has the advantage that it can be dosed at any time in the cycle ; it detects ovarian failure at an earlier stage than do assays of FSH and estradiol This is explained by the fact that AMH is a marker best correlated with AFC (antral follicular count) and may also reflect the quality of the ovarian reserve..- ultrasonographic measurement: On the 2nd or 3rd day of the cycle, it is possible to recognize the pool of follicles which can be recruited during the follicular phase of the cycle. The ultrasound measurement, called the AFC, is a means to predict response to plurifolliculaire ovarian stimulation. The more AFC is weak ,the more the chances of ovarian response is low, even if we increase the intensity of hormonal stimulation. The limit of this method is that its accuracy may vary according to the sonographer and also depends on the quality of the device.
Conclusion :
The measure of ovarian reserve is part of the examination prior to the LDCs (Medically Assisted Procreation), although it is not yet proven that this is essential. This means that, despite a normal ovarian reserve for her age, a patient identified as a "poor responder" on stimulation can sometimes have good chances of pregnancy.In addition, there is still no consensus on thresholds and techniques for measuring ovarian reserve, as many areas remain to be explored.However this measure can provide useful information to patients and, in case of early decline in ovarian reserve, allowing faster access to couples to LDC.
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Victor Hugo