Embryo implantation is the process in which the human embryo adheres to the endometrium, where it continues developing. The first step of this process begins with the dialogue between the embryonic and maternal cells.
This is an extremely complex process that is currently only partially known and depends on the embryo quality, uterine receptivity and their synchronisation.
The key to this process is determined by many molecules segregated around the endometrium and embryo that must be perfectly synchronised in order to maintain this dialogue between the embryo and endometrium.
If we consider that the implantation can be a conversation with perfectly designed words and letters, we can picture its sentences as the stages of implantation and the words as the molecules involved in each state.
Apposition or receptivity dialogue
It begins with the dialogue between the embryo and endometrium, which acquires receptive properties through local growth hormones and factors. This phase is called apposition and is where known factors come into play, such as Natural Killer cells, immunoglobulins and granulocyte colony-stimulating factors.
Embryo adhesion to endometrium
The next stage is called embryo adhesion, in which the embryonic cells look for the best place to adhere to the endometrium, the inner layer of the uterus, through its receptors.
In the next stages the embryo first has to induce the destruction of the surface layer of the endometrium and then invade the deeper levels until it reaches the blood vessels that irrigate it.
Despite all the conducted research, there is still limited knowledge about the molecules involved in each process and their importance.
Treatments to favour the embryo nesting into the maternal endometrium
Most clinical treatments are designed to be included in the apposition phase, in which they aim to increase endometrial receptivity by either administering influential substances in this step or inhibiting others that may adversely affect it. It’s important to be extremely cautious since these are experimental treatments that have yet to show clear therapeutic benefits. The side effects of some proposed therapies should also be considered. Therefore, it is important to apply treatments based on evidence. A clear example of this can be seen in the use of immunosuppressants, meaning drugs that change the organism’s immune response against high counts of Natural Killer Cells that have proven ineffective and cause adverse side effects.
Non-invasive ultrasound markers have been proposed in order to study the microvascularization and uterine structural pattern.
At Instituto Bernabeu, we have applied powerful technology to high-precision ultrasound equipment, which provides us with reliable studies of the endometrial structure to diagnose and treat uterine defects that hinder or block the implantation process.
These studies are extremely useful to patients who have gone through previous treatments without achieving embryo implantation and to those who have had repeat miscarriages.
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