Question

Which type of placenta is found in a rat?
(A) Epitheliochorial
(B) Haemochorial
(C) Hemoendothelial
(D) Endotheliochorial

Answer 1

Hint: The placenta is a temporary organ that develops in the uterus of a female parent during pregnancy and connects the developing foetus with mother.

Complete answer:
The placenta develops in the uterus (womb) of the female parents and connects developing foetus to mother and destroys after the birth of the child. The oxygen demand, nutrients and food requirements of the developing foetus are fulfilled with the help of the placenta. The waste material excreted from developing embryos are also removed from the baby’s blood with the help of placenta. On the basis of histological relationship established between the chorion and the uterine wall, the placenta can be categorised into the following types:
1. Epitheliochorial placenta: This is the simplest type of placenta. This type of placenta is formed by establishing a contact between the chorionic epithelium and uterine epithelium. It is the most primitive type of placenta and all the six tissue barriers are present. Examples of epitheliochorial placenta possessing animals are pigs, lemurs.
2. Hemochorial placenta: The endothelium of maternal parent or uterine blood vessels disappears in Hemochorial placenta. Examples of hemochorial placenta bearing animals are man, apes etc.
3. Hemoendothelial placenta: The foetal capillaries come in direct contact with maternal blood in hemoendothelial placenta. The chorionic epithelium and mesoderm disappear. Examples are Rat, Rabbit etc.
4. Endotheliochorial placenta: The chorionic epithelium comes in direct contact with the endothelium of the maternal blood vessel in endotheliochorial placenta. The uterine epithelium and connective tissue disappear. Cat and dog are examples of animals that possess endotheliochorial placenta.
The type of placenta found in rats is Hemoendothelial.

Hence, the correct answer is option (C).

Note: If a mother’s body tissue is damaged the foetal cells take part in repairment. There are several other ways, other than the ones explained above, in which placenta can be categorised.