Question

State the role of the placenta in the development of an embryo.

Answer 1

Hint: Placenta is the temporary organ, which allows the developing fetus to connect the umbilical cord to the uterine wall through the placenta, and it has so many functions, includes the exchange of nutrients from the mother, and respiratory gases, etc.

Complete answer:
- In some mammals like humans, the placenta is called Chorioallantoic placenta, because it is developed from Chorion and allantois membranes.
- The human Placenta is generally 9 inches in thickness, and 2.5 cm or 0.8 inches in thickness, where this placenta is thickest in the center and thinner in the edges.
- It is typically 500gms in weight.
- The color of the placenta is reddish-blue in color.
- The umbilical cord of the fetus is generally connected by the placenta, and the length of the umbilical cord is approximately 24 inches.
- The umbilical cord, in turn, contains two umbilical arteries and veins.
- In humans, there are almost 20,000 expressing genes for proteins, out of which 70% of them are found in the placenta.
- Among them, 350 genes are almost expressed in the placenta and 100 genes are approximately specific for the placenta.
- When coming to development, during the blastocyst stage, the outer trophoblast of the blastocyst is converted to the placenta, and it has two-layer cytotrophoblasts and syncytiotrophoblasts.
- The blood from the mother flows to the baby through the placenta and approximately 600 to 700 ml of blood flow per min to the fetus through the placenta.

Note: Placenta start expanding and get separated before the time of the delivery and it is detached from the uterine endometrium, and the time between the detachment of the placenta and onset of labor is considered as the 3rd stage of the labor.