The egg donation process is a complex and meticulously process, involving several detailed medical stages, bearing in mind that protocols may vary depending on the medical team. Here is a detailed description of each of these stages:

1. Donor health check and fertility assessment: before the egg donation process begins, the donor undergoes a comprehensive health check. This includes a detailed analysis of her family history, in-depth clinical examinations and rigorous biological tests. These tests are subject to very strict regulations to guarantee the safety of the process.

2. Resting the donor's ovaries: before stimulating egg production, the donor's ovaries are put into a resting state using specific medication.

3. Donor stimulation: stimulation of the donor's ovaries is a critical stage, lasting about 10 to 12 days. It consists of daily subcutaneous injections to stimulate the maturation of several eggs. Throughout this period, regular blood tests and ultrasound scans are carried out to carefully monitor the response of the ovaries to the stimulation. These tests are also used to determine the exact date of the last injection, which will be given 35 to 36 hours before the eggs are harvested.

4. Synchronisation of cycles and preparation of the recipient's uterus: at the same time, it is essential to synchronise the cycles of the donor and the recipient. The recipient is prepared to receive one or more embryos by means of hormone treatment based on oestrogen and progesterone.

5. Egg retrieval: this is a delicate stage which is monitored by ultrasound. It is generally carried out under local anaesthetic and intravenous sedation to ensure the donor's comfort. The procedure takes about 20 minutes.

6. Sperm collection: sperm from the male partner (or a donor) is collected at this stage or used if it has been previously frozen.

7. Egg fertilisation and embryo culture: the harvested eggs are fertilised with the male partner's sperm using various methods, such as conventional IVF, ICSI, PICSI or IMSI. The resulting embryos are then placed in a controlled environment similar to an incubator. Biologists constantly monitor cell division, according to the normal development of an embryo. For example, on the second day, the embryo has 4 cells, on the third day 8 cells, and so on. On the fifth day, the embryo reaches the blastocyst stage made up of 32 to 64 cells.

8. Embryo selection and implantation: mature embryos are carefully selected according to their quality. They are then implanted into the recipient's uterus, usually 3 to 5 days after fertilisation. The implantation procedure is painless and is carried out using a very fine catheter guided by ultrasound.

This detailed description of egg donation treatment highlights the complexity and precision of each stage of the process, demonstrating the commitment of the medical teams to ensuring the success of this fertility procedure.