Chorionic Villi in Human Placenta

The chorionic villi are also known as placental villi and these are found on the placenta during the pregnancy period in females. These villi sprout from the area of the chorion in order to ensure that the area of contact with the maternal blood is maximized. The chorionic villi tend to play a very important role in the entire duration of pregnancy. 

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It is known to all that the placenta is formed by the interdigitation between the maternal and fetal layers. Hence, these villi are basically a product of conception. There are certain branches present in the umbilical arteries that carry the blood in the embryo to the villi. After the process of circulation of blood is complete by passing through the capillaries present in the chorionic villi, the blood will be transferred to the embryo via the umbilical vein. Villi are essential parts of the border that exists between the fetal and maternal blood during the entire pregnancy period. 

The Classification of Chorionic Villi 

The chorionic villi can also be properly classified on the basis of the relations that these have. The floating villi tend to float in a free manner in a particular space which is termed as the intervillous space. These villi tend to exhibit a particular bi-layered epithelium that consists of the cytotrophoblasts that have overlaying syncytium. Apart from that, the anchoring or the stem villi tend to stabilize the mechanical integrity that is present in the interface of the placental and maternal region. 

Different Stages of Chorionic Villi Development 

It is during the primary development stage which is during the end of the fourth week where the chorionic villi are pretty small and are nonvascular. These villi contain the trophoblast. During the beginning of the fifth week, the villi enter the secondary stage of development. It is during this stage that the villi tend to ramify and also increase in size. The growth of mesoderm occurs and the villi contain both the trophoblast and the mesoderm. 

During the fifth to sixth week of pregnancy, the tertiary stage of development begins. It is during this stage that the growth of umbilical vessels takes place and it develops into the mesoderm properly. Hence, the chorionic villi are vascularized. At this point, the constituents of the villi include the trophoblast, blood vessels, and mesoderm. 

The embryonic blood is transported to the villi with the help of the branches that are present in the umbilical arteries. The chorionic villi are hence extremely essential when it comes to the process of pregnancy. 

Clinical Significance of Chorionic Villi 

There are many uses of the chorionic villi from a clinical perspective. 

• Prenatal Diagnosis 

It was in the year 1983 when an Italian biologist by the name of Giuseppe Simoni discovered a particularly new method for prenatal diagnosis using the chorionic villi. The process in today’s time is known as Chorionic villus sampling. It is basically a test that can be used in order to find different problems associated with the fetus. Some of the main diseases that are included in the list of diseases found by chorionic villus sampling are chromosome defects, Tay-Sachs diseases, hemophilia, and genetic disorders. The testing is basically done during the early stages of pregnancy. 

• Stem Cell

The chorionic villi or placental villi have a huge number of stem cells in them. Hence, the studying and testing of these different stem cells can lead to different discoveries. 

• Infections

Some of the recent studies have indicated that the chorionic villi might also be susceptible to certain viral and bacterial infections. It is according to the recent findings that the ureaplasma parvum can result in the infection of chorionic villi in pregnant women. Hence, it also affects the outcome of the pregnancy. 

• Early Miscarriage 

In the cases of early miscarriage in women, there are certain findings related to the presence of chorionic villi in the expulsions of pregnancy. These findings are the only definite form of confirmation that an intrauterine pregnancy took place in the body of the female rather than an ectopic pregnancy. 

The chorionic villi can be defined as the small, finger-shaped outgrowths that are situated in the placenta. The placenta is formed by the interdigitation between the maternal as well as the fetal layers. The cells of chorionic villi tend to have the same genetic material that is found in the cells of the baby. With the help of the revolutionary method known as Chorionic Villus Sampling or CVS, there is a huge scope for finding out important health conditions that the fetus might be suffering from. The sample of the chorionic villi cells is taken for the test and the test results divulge important details regarding the diseases as well as any signs of intrauterine miscarriage as seen in females.