Two gametes in a zygote: the child is already there
It so happens the union of two cells, called gametes. It is of special cells because, unlike all the cells of the body, the bearers of a pair of chromosomes, each gamete carries a single chromosome. And it is only thanks to the meeting that the couple comes together, giving birth to a boy, if the union is between the X chromosome and the Y chromosome, or a female, they are both X chromosomes. The fertilized cell, called a zygote, not only embodies the sex of the baby, but his entire DNA genetic features, color of eyes, skin, hair … all in one tiny cell.
From zygote to morula to three days after fertilization
Just 30 hours after fertilization, when it is still in the bulb tubal, the new biological unit begins to segmentation into two, then four, eight and meanwhile starts to move to make a trip back to the uterus, where he arrived about 3 days after fertilization: zygote now has become a morula, which is a cluster of 12-14 cells just like a small blackberry.
The implantation in the uterus
Once the morula has entered the uterus, the replication activity continues unabated, and so more and more complex: from morula, the agglomeration of cells is called a blastocyst and seven days after fertilization can already distinguish two types of cells : the trophoblast, which will give rise to the trophoblast (early draft of the placenta) and the amniotic membrane, and thermoplastic, which give rise to the embryo.
This is the time when the so-called claustrophobia invasion takes place: the claustrophobia cells from damage you do to get in contact with the cells of the econometric, as it will be called from now on the mucous membrane lining the inside of the uterus, ask for permission to join and establish a relationship of muscularity, to form a vascular network so busy over the months that will allow the passage of nutrients and oxygen from the mother to the fetus. After the invasion, ending the process of embryo implantation.