Depending whether a classical in vitro fertilization (IVF) or (ICSI) will be applied, there are key differences in the preparation of the oocytes for fertilization and in the laboratory process itself.

Classical IVF:

The eggs are cleaned delicately from unnecessary cells and transferred into a container with a nutrient medium and then labeled with your names. Then the pre-treated, processed and activated sperm cells, in a certain concentration, are added. The container with the nutrient medium is put back into the incubator.

The aim is one of the sperm cells to fertilize the egg by itself.

This method is applied when there is an expressed female factor and when the man’s spermogram parameters are in the norm or there are no parameters that do not considerably conform to the norm.

On the following day the eggs are checked for signs of fertilization - the presence of two pronuclei inside the oocyte, a male one and a female one. The fertilized eggs are called pre-embryo or zygote. Over the next two to five days, when they are going to become embryos, they will be closely observed and evaluated for proper cell division and quality.

You will be informed in detail by our embryologists by telephone about the progress of their development.

On the day after the puncture you will know the outcome of the fertilization - the number of fertilized eggs. You will be given instructions when you will receive further information.

Usually we provide more detailed information on embryo developments on the third day and the fifth day, but in some cases it may happen on any one of the days.

ICSI (intracytoplasmic sperm injection)

ICSI is a method of fertilization, in which only one sperm cell is injected into the interior of the egg and thus its partitions are overcome.

IMSI can be also applied in ICSI - this is the step when, under a high microscopic magnification, is selected a proper sperm cell that has a regular shape and size and no defects on its individual parts (head, neck and tail) in order to be injected into the egg.

In the method of ICSI the oocytes are "shedded" - the cumulus cells are enzymatically and mechanically removed. After their maturity and quality have been assessed under a microscope, the fertilization is conducted. The manipulation is performed with the use of a micro-needle and under a microscopic control with a special tool-micromanipulator, that allows the embryologists to perform micromanipulations, and thus to enter into the microcosm of the germ cells.

One captured sperm cell is injected in the egg. The micro-needle has previously passed through the shell of the egg, pellucida zone and the membrane of the egg.

The injected egg is placed in a suitable medium in an incubator. The result of the fertilization and the presence of pronuclei can be seen on the next day. The development is observed periodically, like in the classical IVF.

Prerequisites for ICSI application:

ICSI is applied when: the quantity of your partner’s sperm is too small, or when his sperm cells are not mobile enough, when his sperm cells have a poor structure (morphology), and when the sperm cells are obtained by testicular biopsy.


The answer to this question is not unequivocal, so discuss your options with your physician.

The choice of the one or the other method (IVF or ICSI) depends on many factors, such as the age of the woman, whether she has been pregnant before, the reason for not being able to conceive now, the number of the sperm cells, the number of the eggs removed during the puncture procedure, their quality and other characteristics.

Both methods can be applied when there are more eggs taken out via a puncture procedure and a relatively good semen analysis.

Legend of embryonic development

Day 0: The day of your puncture.

Day 1: There are two pronuclei formed in the fertilized egg (zygote): one from the sperm cell and one from the egg. Not all eggs, collected via the puncture procedure, are suitable for fertilization. Some eggs need more time, at least till the second day when the final result can be seen.

Day 2: The fertilized eggs have divided into 2-4 cells.

Day 3: The proper embryo has divided into eight cells, called blastomeres.

Day 4: Stage morula: the embryo has divided into 12-16 cells.

Day 5-6 day: Stage blastocyst: the embryo now has about 110 cells that form two types of tissues: inner cell mass, from which the fetus develops further, and trophectoderm, from which later the placenta will form, as well as the umbilical cord and the fetal membranes.

This is the maximum amount of time (5-6 days) in which your embryos can be stored in laboratory conditions.

On each of the days in this stage the embryologists observes the development of your embryos.
The process also involves checking and monitoring of the division of the embryo cells (the number of the cells), whether the cells are equal, symmetric, whether there are any fragments, their compact condition, the size and the quality of the blastocysts.


The growth analysis of the embryo development is performed by conventional methods for observation under a microscope, but in many cases we use the most advanced system for cultivation and monitoring of the embryos, called Embryoscope.

The Embryoscope features a most advanced combination of an incubator with a built-in microscope, a camera, and specialized software for monitoring and analyzing the embryo development.

It is an integrated system that allows the embryos to be observed without being taken out of their specific environment, in which they are placed.

The system can track 24 hours uninterruptedly the important parameters, such as the temperature and the gases.
The camera captures the development of the embryo every 10 minutes, in seven different planes.

Unlike conventional monitoring with a microscope, the embryoscope allows us to observe the development in dynamics, which means that we can track and analyze in detail the division and changes in the morphology of the embryo at any stage of its development.

Thus, the system provides great opportunities in terms of selection of those embryos that have the highest implantation potential.

The data obtained via the analysis are stored and can be used for in-depth studies.

Nadezhda Hospitalhas three embryoscopic systems and each of them can be used for cultivation, monitoring and analysis of 12 embryos of six individual patients at the same time.

We are able to track and monitor the development of 216 embryos simultaneously.

When is the use of Embryoscope recommended?

  • After several unsuccessful attempts "in vitro" the Embryoscope can help us find the causes of implantation failure, if the case refers to the so-called embryo "quality". This fact can be established by tracking the entire process of the embryo development: from the moment of the fertilization of the egg until the day of its transfer.
  • Poor embryo quality in previous experiments;
  • For the purposes of the pre-implantation diagnosis;
  • When the number of eggs is smaller, it provides a better environment for the embryo development.
  • When the obtained embryos are more in quantity, we are able to perform a careful selection of those ones, that have the greatest potential for implantation.
  • Luteal support

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