Question

Which one is not a character of the haemochorial placenta?
A. Co2 and excretory products pass from foetus to mother's body
B. O2 and nutrients from mother's body enter the foetus
C. Chorionic villi are covered by blood sinuses of mother
D. It protects the foetus from mechanical shocks.

Answer 1

Placenta is defined as a temporary organ that develops in the nursing mother during pregnancy to support the growth of the foetus. It connects the developing foetus with the uterine wall via the umbilical cord to allow for the movement of nutrients, elimination of waste products, thermoregulation via the mother’s blood.

Complete answer: The placenta is known to be the defining feature of most mammals. It helps to fight against infections and to produce hormones that support pregnancy and for the growth of an embryo. It has two components having both maternal and fetal tissues. The fetal placenta the part of the chorion develops from the same blastocyst that develops the embryo and the maternal placenta formed by maternal uterine tissue. Although in all mammals the function of the placenta is the same but they have different structures microscopically and also at a gross level. The placenta of dogs, pigs, horses, cattle, and humans have differences in structure and gross differences both.
There is classification a based on placental shape and contact points found in different species:
Diffuse- in horses and pigs.
Cotyledonary- in ruminants.
Zonary- dogs, cats and elephants.
Discoid- primates and rodents.
A classification which is based on layers between both the tissues I.e. histological classification.
Epitheliochorial- horses, swine
Endotheliochorial- dogs and cats.
Hemochorial- humans, and rodents.
Option -A- Co2 and excretory products pass from foetus to the mother's body: One of the primary functions in all forms of the placenta is it carries removal of waste products. Carbon dioxide and waste products are removed from the developing foetus via blood circulation through the placenta.
Option -B- O2 and nutrients from the mother's body enter the foetus: The placenta as a temporary organ has one its function to supply nutrients and oxygen to the developing foetus. It is a common feature of all types of placenta.
Option -C- Chorionic villi are covered by blood sinuses of mother: In humans having the hemochorial type of placenta chorionic epithelium is bathing in the maternal blood because the chorionic villi are developed through maternal endothelium. These villi invade maternal endothelium. So they are directed by the blood.
Option -D- It protects the foetus from mechanical shocks: There is no as such known function of the haemochorial type of placenta to protect the foetus from any type of mechanical shock.
So, the correct answer to this question is the option” D”

Note: The very important function of planners includes passing of immunoglobulins from mother to its foetus. It provides passive immunity to the foetus and the antibodies IgG is passed to the foetus providing immunity to the foetus from any infection.