Human embryos from the test tube
In early pregnancy, a structure called a blastocyst develops from the fertilized egg. Now it has been possible to create such structures in the Petri dish - and thus to create model systems with which embryonic development can be better researched.
The better we understand embryonic development, the easier it is to improve the success rate of artificial insemination and prevent miscarriages and growth defects. However, there are major hurdles to researching early embryogenesis: human embryos are lacking and scientific work is subject to strict ethical and legal restrictions. Techniques that allow the creation of embryo-like structures from cells that are grown in vitro (in a test tube) offer a possible way out.
Two new methods now cause human embryonic stem cells and reprogrammed body cells to organize themselves in a Petri dish - into structures that resemble early human embryos. The cell types in it correspond to those that produce the fetus and the tissues that support it in real pregnancies.
In mammals, a fertilized egg cell undergoes several cell divisions in the first few days of its development, which leads to the formation of the ball-like bladder nucleus ("blastocyst")…