chorionic villus

Examples of chorionic villus in the following topics:

• Prenatal Diagnostic Tests

  • ., amniocentesis (that can be done from about 14 weeks gestation up to about 20 weeks), and chorionic villus sampling (that can be done earlier: between 9.5 and 12.5 weeks gestation).
  • Chorionic villus sampling is associated with slightly more risk to the fetus.
  • Since chorionic villus sampling is performed earlier in the pregnancy than amniocentesis, typically during the first trimester, it can reasonably be expected that there will be a higher rate of miscarriage after chorionic villus sampling than after amniocentesis.
  • Because of the risk of miscarriage and fetal damage associated with amniocentesis and chorionic villus sampling procedures, many women prefer to first undergo screening so they can find out if the fetus' risk of birth defects is high enough to justify the risks of invasive testing.

• Fetal Circulation

  • Oxygen then diffuses from the placenta to the chorionic villus, an alveolus-like structure, from which it is carried to the umbilical vein.

• Down Syndrome

  • Genetic counseling along with genetic testing, such as amniocentesis, chorionic villus sampling (CVS), or percutaneous umbilical cord blood sampling can be offered to families who may have an increased chance of having a child with Down syndrome, or where normal prenatal exams indicate possible problems.

• Development of the Extraembryonic Coelom

  • The extra-embryonic coelom is a cavity that contains the chorion.
  • The extra-embryonic coelomic cavity is also called the chorionic cavity—it is enclosed by the chorionic plate.
  • It is the fetal aspect of the placenta that gives rise to chorionic villi.
  • The chorion is one of the membranes that exist during pregnancy between the developing fetus and the mother.
  • Blood is carried to the villi by the paired umbilical arteries, which branch into chorionic arteries and enter the chorionic villi as cotyledon arteries.

• Chorionic Villi and Placental Development

  • In the placenta, chorionic villi develop to maximize surface-area contact with the maternal blood for nutrient and gas exchange.
  • Chorionic villi sprout from the chorion after their rapid proliferation in order to give a maximum area of contact with the maternal blood.
  • During the primary stage (the end of fourth week), the chorionic villi are small, nonvascular, and contain only the trophoblast.
  • Chorionic villi are vital in pregnancy from a histomorphologic perspective and are, by definition, products of conception.
  • Image illustrating the placenta and chorionic villi.

• Implantation

  • The syncytiotrophoblast then implants the blastocyst into the endometrium of the uterus by forming finger-like projections into the uterine wall called chorionic villi.
  • The chorionic villi grow outwards until they come into contact with the maternal blood supply.
  • The creation of chorionic villi is assisted by hydrolytic enzymes that erode the uterine epithelium.
  • Human chorionic gonadotropin is the hormone that is detected by pregnancy tests, as it is found in the maternal bloodstream and urine.
  • During implantation, extensions of the trophoblast, the syncytiotrophoblasts, embed within the endometrium and form chorionic villi.

• Absorption in the Small Intestine

  • Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface.

• Histology of the Small Intestine

  • Intestinal villi (singular: villus) are tiny, finger-like projections that protrude from the epithelial lining of the mucosa.
  • Each villus is approximately 0.5–1.6 mm in length and has many microvilli (singular: microvillus), each of which are much smaller than a single villus.

• Fourth Week of Development

  • The chorion undergoes rapid proliferation and forms numerous processes.
  • The chorionic villi, which invade and destroy the uterine decidua and at the same time absorb from it nutritive materials for the growth of the embryo.
  • Until about the end of the second month of pregnancy the villi cover the entire chorion, and are almost uniform in size, but after this they develop unequally.

• Early Pregnancy Tests

  • ., human chorionic gonadotropin (hCG).
  • The first of these markers to be discovered, human chorionic gonadotropin (hCG), is produced by the trophoblast cells of the fertilized ovum (blastocyst).
  • Most chemical tests for pregnancy look for the presence of the beta subunit of hCG or human chorionic gonadotropin in the blood or urine. hCG can be detected in urine or blood after implantation, which occurs six to 12 days after fertilization.