If earlier biologists spoke only hypothetically about the asexual reproduction of mammals, then in 2022 the results of an experiment on mice appeared, which showed the success of new technologies. Why can women reproduce on their own and men cannot? What methods of asexual reproduction exist today? Will girls born of only one mother be like two drops of water like her? Will there come an era when you only need to take a pill to get pregnant? And above all - are we in danger of a world without men like in the movie Sexmission?
Scientists call asexual reproduction parthenogenesis - a Greek word meaning literally "virgin creation" (from Greek Parthenos - virgin, genesis - creation). Parthenogenesis occurs in a wide variety of organisms, including plants, insects, fish, reptiles, and even birds.
Until recently, scientifically confirmed cases of parthenogenesis in mammals, including humans, have not been documented. Although, hypothetically, women are able to start reproducing their own kind without the involvement of men, because they have everything in their bodies to do so.
Females have two X sex chromosomes, one from their father and one from their mother. Men receive X from their mothers, and from their fathers a small addition of Y, in which there are almost no genes. But the most important thing is that men do not have reproductive structures to bear children.
With the development of genetic technologies, including genome editing, scientists began to develop methods of artificial parthenogenesis. In 2022, biotechnologists from Shanghai, China, succeeded in this field by publishing the results of their experiments on mice in the prestigious scientific journal PNAS. Female mice were able not only to become pregnant, but also to give birth to full-fledged offspring. Several females "conceived" by artificial parthenogenesis have also successfully become mothers, convincing the scientific community that asexual reproduction in mammals is possible.
The sperm's contribution to mammalian reproduction is necessary not only because it carries the missing half of the genome. It carries the factors that initiate the proper development of the embryo. Not only the genes should come from the sperm, some of them should be in a special state. These initiating factors are necessary for the cell to start dividing and developing, turning it into an embryo.
What did the scientists from Shanghai do? They modified the "female" genes, giving them the desired state in immature eggs (oocytes) whose maternal haploid (half) genome was completed to the diploid (full) chromosome set by injecting the other half of the maternal genome - it was like fertilization simulated.
The other half of the genome was taken from the so-called polar body, which is formed during meiosis (division of the nucleus of a eukaryotic cell with the number of chromosomes halved) during the formation of mouse eggs. This is what started the process of turning the cell into an embryo. The main conclusion that can be drawn from this successful experiment is that a phenomenon such as parthenogenesis can be controlled.
If it can be controlled in mice, the next step is to try this technology on monkeys. Then it will probably be tried on human cells in those countries where it is allowed to work with human stem cells at the earliest stages of embryo development. But if it worked in mice, it will 100% work in humans!
It is clear that women with the help of artificial parthenogenesis technology will only be able to give birth to girls. And these - to give birth to new girls, continuing only the female gender. It is very similar to the world presented in the Polish science fiction film Sexmission.
Will the girl born of the mother by the method of "immaculate conception" presented in the work of scientists from Shanghai be similar to her? Probably not, because for this purpose, half of the genome is taken from one oocyte (immature egg) and the other half is taken from the direction body of another oocyte. In such a cell with a complete set of chromosomes, there will be a slightly different combination of genes, but the similarity to the mother will be very high.
However, there is another mechanism by which it is possible to give birth to a girl from the mother, without the participation of the father. By disrupting meiosis during egg formation, which is known to occur in mammalian female fetuses during intrauterine development, unreduced eggs with a full chromosome set can be produced, followed by the initiation of ovulation with further epigenetic reprogramming of the ovum and initiation of fetal development. In this case, the developed baby will be an exact copy of the mother.
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