<P> Researchers from MERLN Institute and the Hubrecht Institute in the Netherlands managed to grow samples of synthetic rodent embryos, combining certain types of stem cells . This method will help scientists to more deeply study the very first moments of the process of the birth of a new life, which, in turn, can lead to the emergence of new effective methods to combat infertility and other genetic diseases . </P> <P> Fossilized animal embryos are known from the Precambrian, and are found in great numbers during the Cambrian period . Even fossilized dinosaur embryos have been discovered . </P> <P> Some embryos do not survive to the next stage of development . When this happens naturally, it is called spontaneous abortion or miscarriage . There are many reasons why this may occur . The most common natural cause of miscarriage is chromosomal abnormality in animals or genetic load in plants . </P> <P> In species which produce multiple embryos at the same time, miscarriage or abortion of some embryos can provide the remaining embryos with a greater share of maternal resources . This can also disturb the pregnancy, causing harm to the second embryo . Genetic strains which miscarry their embryos are the source of commercial seedless fruits . </P>

When does a zygote turn into an embryo