Allantois

Allantois is one of the extraembryonic membranes of reptiles, birds and mammals. It is an outgrowth of the posterior part of the digestive system of the embryo, which serves as the embryonic bladder or the source of the formation of blood vessels of the chorion and placenta.

In reptiles and birds, the allantois performs mainly the function of the bladder, accumulating the products of nitrogen metabolism. In mammals, the allantois plays an important role in the formation of the placenta, providing gas exchange and nutrition to the embryo. The blood vessels of the allantois grow into the tissue of the chorion, forming the basis of the placental circulation. Thus, the allantois is a necessary structure for the development of embryos in reptiles, birds and mammals.

Allantois: organ important for embryo development

The allantois is an organ that plays an important role in the development of the embryo of mammals, birds and reptiles. It is part of the embryonic membrane, called the amniotic sac, which surrounds the embryo and provides it with protection and nutrition.

The word "allantois" comes from the Greek words "allantos", meaning "sausage", and "-eides", meaning "similar". This is due to the shape of the organ, which resembles a sausage.

The function of the allantois is to control the exchange of gases and wastes between the embryo and the environment. As the embryo develops, the allantois begins to fill with fluid, which contains metabolic waste. This fluid later leaves the embryo through the umbilical canal.

In addition, the allantois plays an important role in the formation of the placenta in mammals. During pregnancy in animals, the placenta serves as a link between mother and embryo, providing nutrition and oxygen. The allantois contributes to the formation of the placenta by forming a vascular network that later connects with the vessels of the maternal placenta.

Interestingly, allantois is also used in medicine to produce vaccines and medicines. For example, vaccines against influenza and chickenpox are produced using cells grown from the allantois of a chicken egg.

In conclusion, the allantois is an important organ that plays a key role in embryonic development in mammals, birds and reptiles. It ensures the exchange of gases and wastes, and is also involved in the formation of the placenta in mammals. In addition, allantois has wide medicinal uses and is used to produce vaccines and medicines.

Allantois is a transparent, non-vascular lining located at the head end of the embryo and prevents the penetration of microorganisms to it at the time of its implantation into the uterine mucosa during pregnancy.

The allantois is located in the body of the embryo above the amnion and the umbilical cord. The thickness of the transparent lining is about 0.2 mm. The main cells of its body continue into the atrial complex, through which the vessels and nerves of the umbilical cord pass. Fertilization of cells is carried out with the help of the Gametofete, during which they are transported into the body of the embryo from the epibolum, by a specific opening (primary pronucleus), which occurs even before moving to the mother’s body. The Gametofete then penetrates between the cells of the amnion and is destroyed in this space, where the Gamete cells become the ordinary nucleus of the zygote, and the degenerating Gametobe substance is directly divided to ensure uniform distribution throughout the developing body, which includes the allantois itself. Thus, the allantois is a donor of precursors necessary for the growth and development of the fetus.

Although the embryo is connected to the mother's body by the placenta, it receives all the necessary nutrients through the umbilical cord, as well as gases produced in the mother's body, through a narrow space between the body of the allantoid and the placental membrane, which is called the Choriopher. This is how the fetus is protected and gases from the mother’s body are released to the outside. After approximately 40 days after fertilization, the allantoid, for example, disappears.

But under certain conditions, the fruit may not be surrounded by allantoid. For example, in twins, if the pregnancy is complicated by a transverse or breech presentation, the maternal uterus is formed by one large collection, called a “single sac,” and individual branches of the allantoids disappear, causing a causal delay in the development of one or both fetuses, which usually leads to their antenatal regression.