In Vitro Maturation of oocytes (IVM)

Every woman’s body is born with a number of oocytes exceeding two million. These oocytes are initially at an immature stage that lasts for many years. The transition to puberty marks the beginning of their ripening through each month’s ovulation.

Every month, the female body prepares around 20 oocytes for the final maturation stage. Although only one of these will proceed to ovulation, almost all the other oocytes can be matured and fertilised. With the completion of ovulation, however, all other oocytes of this cycle will inevitably proceed to degeneration and eventually be absorbed by the body itself.

Since the middle of last century, we have known that human oocytes can complete the final stages of maturation in laboratory conditions. This in vitro maturation of oocytes, combined with the knowledge that these oocytes can also be fertilised in the laboratory, laid the foundations for the development of a new field in the facilitation of human reproduction, known as In Vitro Maturation (IVM).

The first great advantage of in vitro maturation of oocytes for a woman is that it minimises the use of hormonal drugs. As such, treatment with vitro maturation closely resembles IVF treatment in a natural cycle, with the advantage of harvesting multiple oocytes instead of one, during the natural cycle. The fewer drugs used, means fewer possible side effects during treatment and over the longer term.



In particular, the restricted use of drugs minimises the possibility of developing oocyte hyper-stimulation syndrome, which is the most severe complication of IVF treatment. Although hyper-stimulation syndrome in a severe form is fortunately rare, there are women, mainly with a polycystic ovary syndrome (PCOS), with a higher risk of developing it. Today, women with PCOS are considered the most appropriate population for whom the application of in vitro matured oocytes can generate a high maturation rate, fertilisation and implantation, while at the same time avoiding the dangerous consequences of ovarian hyper-stimulation syndrome.

The oocyte harvesting method within the in vitro maturation programme is a similar procedure to conventional IVF. Using ultrasound, the size of the follicles and endometrial thickness are estimated and the time for oocyte harvesting is determined at approximately 10 days after the beginning of the menses. Egg retrieval is performed under mild sedation, making the procedure painless for the woman. The harvested immature oocytes are placed in a specific culture medium for maturing over a period of 1-2 days. At the same time, fertilisation starts in the laboratory. After 2 to 3 days, the most suitable embryos are selected and transferred into the woman’s uterus.

More recently, in vitro maturation started to be applied for women who wish to preserve their oocytes and their fertility before starting a treatment for malignant diseases. Treatments such as chemotherapy and radiotherapy have side effects to the functioning of the ovaries and often lead to ovarian failure and the future inability to produce oocytes. However, with in vitro maturation method it is possible to obtain many immature oocytes, without using hormonal drugs and in a very short time. Thus, no valuable time is lost in starting treatment for malignant diseases. Immediately after collecting the oocytes, in vitro maturation and cryopreservation are carried out for future purposes.

To date, the number of children born worldwide after the application of the in vitro matured oocytes method is less than a thousand. These children, however, are healthy and their development has been normal so far. There is no difference from other children.

Currently, the in vitro matured oocytes method is seeing excellent development. Very soon, it will be a major treatment option for women who want and need to avoid hormone therapy, and for women who wish to preserve their fertility, when facing a serious disease that requires treatment that is particularly aggravating to the functioning of their ovaries. As with any new assisted reproduction method, women need to be carefully screened, after duly informed of its advantages and limitations.


• Embryolab’s well-equipped laboratory environment, combined with the 24-hour monitoring of culture conditions, ensure the ideal conditions for the maturation of immature oocytes.
• At Embryolab, we have systematically preserved oocytes with a very high level of survival, fertilisation and pregnancy rates since 2008.
• Embryolab is one of the few laboratories in Greece and in world with so much experience in oocyte vitrification
• All parameters are systematically controlled