Scientists have always believed that life is after sperm egg combination and fertilization. However, a recent joint study by Chinese and American embryologists shows that there are two sets of independent spindles in human fertilized eggs, that is, during the period from sperm egg combination to the first mitosis, the chromosomes of the parents do not fuse with each other, but remain spatially independent. This means that fertilized eggs at this stage can not be called "life" in the real sense. This new discovery, which subverts the classical theory of biology, was recently published as a cover article in the Journal of assisted reproduction and genetics, a well-known international journal in this field.
Since 2015, Dr. Xu Xiaoming, director of the embryo Laboratory of the reproductive center of Beijing Jiayuan hospital and a well-known embryologist, and Professor Meng Li, director of the laboratory of the reproductive center of Los Angeles, California, have started exploratory research on the first cell mitosis process of human embryos. " For a long time, scientists have believed that during the first mitosis of human embryos, a set of spindles is responsible for separating chromosomes into two cells. In fact, two sets of spindles are involved in the process of chromosome separation, one of which separates male chromosomes and the other separates female chromosomes. " Dr. Xu Xiaoming pointed out that 'compared with the previous theory, this discovery has a more demanding challenge, because as long as there is time or space synchronization between the two sets of spindles, it will cause chromosome separation errors, which better explains the high proportion of chromosome abnormalities in early human embryos.'
At the same time, this discovery also led to rethinking the definition of human 'life'. After fertilization of sperm and egg, the chromosomes of human male parent and female parent are still separated and do not fuse with each other immediately. As we mix blue and yellow pigments, at the beginning of mixing, the two pigments still stubbornly maintain their true colors, but after full mixing, a new color - Green will appear. Therefore, the fertilized egg at this stage cannot be called "life" in the real sense, so the concept of "life initiation" may be redefined.
In addition, the findings of this study are also of positive significance to ethics. At present, Catholic countries, such as Italy, are not allowed to fertilize many eggs at one time, because the previous view was that once the sperm and eggs were combined, it was life, so these countries explicitly prohibited freezing embryos. Each couple receiving assisted reproductive technology can only fertilize 1-2 eggs at a time. If there are remaining eggs, they can only choose to freeze the eggs. However, the efficiency of frozen eggs is much lower than that of frozen fertilized eggs. This finding suggests that fertilized eggs are not real life (male and female chromosomes are still independent of each other). Therefore, in these Catholic countries, fertilized eggs may be directly frozen instead of eggs in the future.
The latest discovery that there are two sets of independent spindles in human fertilized eggs puts forward new challenges and research directions in the field of assisted reproductive medicine. Xu Xiaoming said that at present, the research is still in the preliminary exploration stage, and it is expected to make greater progress in the future, so as to provide impetus for the safe, rapid and efficient development of assisted reproductive technology all over the world.