Amnion vs Chorion: Difference and Comparison

Pregnancy time is one of a woman’s most memorable and life-changing experiences. She goes through many critical changes to welcome another budding human into the world.

From the beginning of the second week of pregnancy till almost the eighth week, the tiny peanut-like structure in a mother’s womb is called an embryo. After the end of eight weeks, it is named a fetus.

So two more crucial names are associated with the embryo: amnion and chorion.

Key Takeaways

  1. The amnion is a thin, protective membrane surrounding the developing embryo or fetus in amniotes, filled with amniotic fluid that cushions and protects the developing organism.
  2. The chorion is an outer membrane that also encloses the developing embryo or fetus, playing a role in gas exchange and nutrient transport, eventually forming part of the placenta in placental mammals.
  3. Both amnion and chorion are crucial structures in the development of amniotes. Still, they serve different functions, with the amnion providing protection and the chorion facilitating gas exchange and nutrient transport.

Amnion vs Chorion

The difference between Amnion and Chorion is their placements near the embryo. Amnion is situated in the internal part of the outer mesoderm, and the inner ectoderm is called the somatopleure.

Amnion vs Chorion

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Comparison Table

Parameters of the ComparisonAmnionChorion
What is it?The amnion is the extra layer that safeguards the embryo and delivers the necessary nutrients.Formed from the mesoderm and the ectoderm, the chorion is a supportive layer to the amnion to provide the utmost care for the evolving fetus.
In whom can you find it?All kinds of mammals and animals offsprings are well refined here except for fishes and amphibians.All the embryos of animals, humans, and reptiles have chorions, and even the role of the placenta is fulfilled in mammals by chorion.
It’s purposeThe ultimate job of amnion is to shield the embryo. It also exchanges the necessary nutrients between the mother and child.Since it exists just above the amnion, the chorion gives the embryo that excess layer of protection.
What are each of them made up of?Amnion is attached to three other essential layers: the sac, allantois, and yolk.Chorion instead forms tail-like structures called the chorion villi, which do the major work of the chorion.
When are their acts influential?At the time of the delivery of the baby.It provides the blood and nutrients for the baby from the mother throughout the pregnancy.


What is Amnion?

It is not a part of the embryo but formed from its tissues. Yolk, sac, allantois, and chorion all together provide shelter to the embryo, exchange of nutrients takes place, and the unwanted waste is removed by amnion.

The process here goes like this: There is a productive part known as the amniotic fluid, like a sac made by the amnion. The fluid protects the baby from any outer impact.

The amnion is said to have closer physical contact with the embryo. It also enhances volume as the embryo grows bigger. 


What is Chorion?

The chorion is one of the two membranes which form the amniotic sac. This sac contains the fluid that breaks when the baby is about to be born.

The villi shoot from the chorion to gain more maternal blood, like the principal liquid at this stage. It safely delivers supplements from the mother’s food to the undeveloped organism.

The chorion villi give the maximum connection between a mother and her unborn offspring. Here the endometrium is attached to the mother’s blood vessels, where all the excretion, blood, nutrients, love, and affection are reached out this way.

Main Differences Between Amnion and Chorion

  1. The chorionic fluid is found in the chorionic cavity, a space between the amnion and the chorion. The amniotic fluid is found inside the amnion itself.
  2. Amnion’s main characteristic is to preserve the embryo, but the chorion protects the baby and provides essential nurturing.
  3. The Amnion has no extra features to make its work easy. Still, the chorion has a crucial element called the chorion villi, which is more capable than the chorion itself.
  4. The Amnion is also responsible for the excellent outcome of the fetus, but as for the chorion, it has to comfort the embryo by all means.
  5. The chorion is in the outermost layer, so eventually, it supplies more security to the embryo, whereas the amnion falls inside the chorion, which also seeks its protection. 


Last Updated : 11 June, 2023

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