Question

Which type of placenta is found in a rat?

• A. Epitheliochorial
• B. Haemochorial
• C. Haemoendothelial
• D. Endotheliochorial

Answer 1

The correct option is C Haemoendothelial

The epitheliochorial placenta is the simplest type with all six tissue barriers present and is the most primitive type. The immediate contact of the two halves of the placenta involves chorionic epithelium and uterine epithelium. E.g., pigs, lemurs.
In the haemochorial placenta, endothelium of maternal or uterine blood vessels disappears. E.g., man, apes.
In the haemoendothelial placenta, the chorionic epithelium and mesoderm also disappear allowing the foetal capillaries to come in direct contact with the maternal blood, thus, endothelial lining of their blood vessels alone separates the foetal blood from the maternal sinuses. E.g., rat, rabbit.
In the endotheliochorial placenta, the uterine epithelium, as well as the uterine connective tissue, break down so that the chorionic epithelium comes in contact with the endothelium of maternal blood vessels. E.g., cat, dog.