Day 7, Implantation
Once the blastocyst has hatched, it is ready to attach to the endometrium. This is called for implantation. We are not able to show this stage inside the womb.
One of our doctors, Ursula Bentin-Ley, has performed research on how the blastocyst implants in the uterus in humans. These are two of her pictures, which show a human embryo that has implanted on a piece of human endometrium grown in the laboratory. This is the closest approach so far to the situation inside the womb.
Ursula's research showed amongst other things, that the cells of the endometrial surface change around the area where the blastocyst has formed contact with the uterine mucosa. These changes are called pinopode formation (see arrow).
Unknown knowledge about the uterine mucosa
The early embryonic development has been studied for many years, until the stage where the embryo is transferred back into the womb. What is happening inside the uterus is only known from laboratory experiments.
There is growing interest to find out what is happening in the endometrium during implantation. Until now we have not been able to define exactly what characterises a receptive endometrium.
However, we have ongoing research collaboration with other clinics abroad to try to find out which factors are necessary for an embryo to implant into the mucosa. It is now possible to perform analyses of an endometrial sample to see whether it contains these known substances.