Polyembryony

As an article on a given topic, it may be difficult to structure and will not cover all aspects of polyembryony, but I will try to do it.

Polyembryony is the ability of embryos from initially different eggs to develop into one living being. In the early stages of embryo development, they are indistinguishable from typical (monoembryonic) individuals, that is, they contain less different developing tissues than is needed for one individual, as if there were two or more of them. Subsequently, they develop at different rates, so that each individual retains its own personal appearance and sets of unique tissue and molecular features. Once one of the embryos is replaced by the surrounding tissue, it may remain in place or "migrate" to some part of the other embryo's body, forming a new organ (as happens with most types of conjoined twins, although not exclusively). The history of observations of polyembryony goes back more than one millennium, and since the middle of the 19th century we have known a lot about what types of polyembryophy can occur with different methods of egg fertilization. If the egg is genetically separated from its closest sperm donor and is fertilized by sperm

Polyembryony or superfetation is a phenomenon in which a multiple pregnant woman produces not only the required embryos in the uterus, but also additional ones. How does this happen?

The embryo can begin to divide more than once - sometimes there are several of them in the womb. Moreover, the close proximity of such division options leads to the formation of many separate fruits - twins. In some women, some of these additional embryos turn out to be abnormally developed - they may not be viable or have no obvious internal organs. Such fruits do not form into full-fledged organisms - they turn out to be superfluous or underdeveloped for a given uterus. Scientists have long established the reason for this phenomenon. This is due to a disruption of the natural mechanism of egg development during fertilization, when two cells divide and one of them attaches to the wall of the uterus. As a result of improper division, it is this cell that divides independently, also forming a second egg. This second egg should become the corpus luteum, which is responsible for producing hormones that help the pregnancy continue to develop. It attaches to the inner membrane of the egg already present there. These two structures then grow together and eventually form the biological female body. However, sometimes this mechanism of “half-life” of a cell with the formation of two eggs occurs over and over again. This could go on forever. The eggs grow, develop in two directions and cause the birth of twins. An additional uterus develops, where another baby develops and is born. This uterus has no connection with the existing uterus, so a woman in labor can have two uteruses at once. It is assumed that initially such a woman already had two uteruses - in total, there were four such organs in her body. However, such a phenomenon cannot be called completely ordinary. Embryotomy, which is extremely rare, involves intervention for an incorrectly positioned embryo that regularly leaves the uterus and returns back. An embryo appears on the surgeon’s table, which was intended to develop in one of the bodies of the uterus, but for some reason left it through the abdominal cavity and ends up in another organ.