Embryo Development – Step by Step

What does the growth and development of an embryo look like in the first days?

Our embryologist Goran Stefanovski explains what happens in the laboratory at each stage of this process.

After fertilization, the first sign of successful fusion of the sperm with the egg is the formation of the polar body and the beginning of the pronuclear phase. The two pronuclei are seen in this early stage, before the zygote begins to divide.

The first division creates a two-cell embryo, which then transitions into a four-cell, and gradually continues to develop into an 8-cell embryo. The synchronization of divisions is an important indicator of the quality of the embryo.

The next step is the formation of the blastocyst – a structure in which the inner cell mass (from which the baby will develop) and the trophectoderm are already differentiating.

Finally, the mature blastocyst expands and becomes ready to return to the uterus, the final step before implantation and the onset of pregnancy.

At Hospital Plodnost, we monitor each embryonic development with state-of-the-art technology, ensuring the best possible conditions for successful implantation.