What is Fertilization?
Fertilization is the natural process by which the sperm unites with the egg, creating the first cell of the new organism – the embryo.
During this union, the genetic material from the mother and father combines:
23 chromosomes from the egg
23 chromosomes from the sperm
combine, forming the 46 chromosomes of the future embryo.
How is fertilization done in the laboratory?
After egg retrieval, the eggs are prepared in the laboratory and placed in a specially controlled environment (ovens) that reproduces the conditions of the female body.
Depending on the characteristics of the sperm and the couple's history, one of two methods is chosen:
1) Classic IVF
The eggs are placed in a culture medium along with the appropriately treated sperm.
The sperm enters the egg naturally, and fertilization is completed within 16–20 hours.
2) Microfertilization (ICSI)
In cases where the natural penetration of the sperm into the egg is more difficult, a healthy sperm is directly injected into the egg using a microneedle.
This method bypasses mechanical or functional obstacles and allows fertilization even in very demanding conditions.
When is ICSI recommended?
The microfertilization method is indicated in cases such as:
Oligospermia (low sperm count)
Asthenospermia (low sperm motility)
Teratospermia (increased morphological abnormalities in sperm)
Surgical sperm retrieval (TESE / PESA)
Previous fertilization failure in an IVF cycle
Unexplained infertility
Using a small or frozen semen sample
When Preimplantation Genetic Testing (PGT) is required
