In a normal pregnancy the embryo usually implants itself in the uterus.

One is the stage when embryos would normally implant in a uterus.

It is only after the mammalian embryo has implanted in the uterus that differentiation and organization of the fetus occurs.

Such a tetraploid embryo can develop normally to the blastocyst stage and will implant in the wall of the uterus.

Every month, the uterus builds up a lining of tissue called the endometrium, where an embryo can implant and grow.

The embryo can also implant in the ovary, the abdomen or the cervix.

As a result, the embryo may not implant in the uterus.

Then began the long wait to see whether the embryo would implant properly, whether the placenta would hold.

The embryo does not immediately implant in the uterus, but remains dormant for a period of time.

The embryos correctly implanted into the artificial uterus' lining and started to grow.