After a life-and-death competition, the sperm finally combines with the egg to produce a fertilized egg. NextThe movement of the fertilized egg from the fallopian tube to the uterus is completely dependent on the peristalsis of the female fallopian tube and the swing of the cilia!
The fertilized egg moves very slowly, for the first 24 hours, it remains motionless in place, on the second day it enters the isthmus of the fallopian tube, and stays in the isthmus for 2 days, where the cells ** develop into mulberry embryos.
It is not until the 4th day that this mulberry embryo enters the uterus. At this time, the uterus has undergone miraculous changes, which is very different from when a large number of sperm passed through 4 days ago. The lining of the uterus becomes as soft as a carpet, and many protrusions like little fingers grow on it, allowing fertilized eggs entering the uterus to attach to it. It's a sight of something, you know? Just like a rock climber who uses protrusions on the rock wall to cling to the rock wall, the difference is that the climber is protected by a harness while the fertilized egg is not protected at all, and this dangerous state lasts for 2 whole days! Therefore, many studies have reported that fertilized eggs can easily fall off the uterine wall during this period.
On the 6th day of entering the uterus, the trophoblasts of the fertilized egg secrete a protease that dissolves the endometrium, dissolving a 1 mm diameter gap in the endometrium, and once the zygote implants into this notch, it is out of an extremely dangerous state.
On the 12th day, the gap is repaired by the tissue of the endometrium, so the entire fertilization and implantation process is completed, and the fertilized egg that returns to the uterus begins a new journey!