After the egg collection process, this time the egg taken from the woman and the sperm taken from the man are fertilized in the laboratory environment. This is the last step before the embryo transfer is performed.
During the egg retrieval (OPU) process, the follicle content that is sucked in is immediately sent to the laboratory. The egg in this liquid, which is examined with a special microscope, is placed in the culture liquid and lifted into a device called an incubator. The incubator keeps the temperature constant at 37 oC and the carbon dioxide rate at the level of 5-6%. Mature egg cells are ready for fertilization after 4-6 hours. After stimulation, mature eggs suitable for fertilization can be obtained from approximately 80% of the follicles with a diameter of 18 – 22 mm.
During the collection of eggs (oocyte) from the woman, the man also gives sperm. Masturbation is the best way to get sperm. In people who cannot find live sperm in their semen, sperm is searched surgically. The semen obtained is taken into a special container and is expected to liquefy. The liquefied semen is examined in terms of sperm count, motility and shape.
The most important criterion in patients who are planned for IVF is the number of motile sperm. The examined sperm are prepared for fertilization. Sperm preparation is important for two reasons. The first of these is to clean the foreign proteins in the semen, and the second is to trigger some reactions to make the sperm hyperactive.
After the egg culture and sperm preparation are completed, the fertilization process begins. Sperm and eggs are laid together. 20,000 sperm are used for each egg cell. This number can be increased in cases where sperm parameters are defective. Microinjection (ICSI) should be preferred in the presence of male factor or in cases of unexplained infertility. 16-18 hours after the procedure, it is checked whether there is fertilization. The number of single cells in the fertilized egg has now increased to two.
Fertilized eggs are put back into the culture medium and are expected to reach advanced stages. When the appropriate stage is reached, a certain number of quality embryos are taken and transferred into the uterus of the woman.