The In Vitro Fertilization performed by Drs. Steptoe and Edwards was a revolutionary step forward in the treatment of infertility. However, this technique, which could solve the problems of becoming pregnant in cases of tube obstruction did not work when there was a low number of motile spermatozoids.

Indeed, when attempting In Vitro Fertilization (IVF) using sperm samples with very low MSR, there was no fertilization..

To solve this problem, several techniques were developed. The first one was the partial dissection of the zona pellucida (PZD). It involved the slight opening of the zona pellucida (the ‘shell’ that covers the egg), with the idea that the spermatozoids could fertilize the egg more easily. Then, sub-zonal insemination (SUZI) was performed. By this technique, the spermatozoids were placed between the zona pellucida and the cell membrane of the egg.

The following step was the introduction of a single spermatozoid inside the egg (ICSI). It was performed for the first time in 1988 by an Italian biologist (Giampiero Palermo).
Since then, the use of ICSI has become more widespread. At the beginning, it was only used in cases of severe male factor. However, today, it is used in many other indications, not only for problems of the spermatozoids (few eggs retrieved, patients older than 38, etc.). Currently, ICSI is used to fertilize the eggs in more than 90% of cases.

ow is ICSI done?
Once the follicular puncture to retrieve the eggs is done, the eggs are processed in the laboratory. When the eggs are in the follicles, they are surrounded by cells (granulosa cells). To perform the microinjection (ICSI) it is necessary to remove the granulosa cells that surround the eggs. This process is usually called ‘to peel’ or ‘to clean’ the eggs.

Once this process is done, the egg is ready for the microinjection. A high precision device (the micromanipulator) is used. This device is a microscope, which has some controls incorporated (which are like joysticks) that controls the movement of two micropipettes. One of these micropipettes serves to hold the egg and the other is used to introduce the spermatozoid into the egg.

The process is repeated with each of the eggs. Then, they are placed in the incubator. In this unit, suitable culture conditions for human eggs are reproduced (temperature, CO2 concentration, etc.).

The remaining process is like In Vitro Fertilization. The following day, the fertilization is confirmed and on the second, third or fifth day (if it is a long culture), the embryo transfer is performed.