<span>Cell death occurs.The way this makes Apoptosis an definition of this that cells has an turnover, an state where there are other cells that must have the information to induce the function of the organ.</span>
About 60% of natural conceptions fail to implant properly. One of the reasons may be the failure of the embryo to generate Trypsin, a chemical which induces a receptive environment in the uterus in order for the fetus to be implanted. The excess or lack of chromosomes of the fertilized egg may also be a factor in implantation failure. A weak immune system of the woman may also be an important factor.
The best answer to fill in the blank is "multilayered membrane."