What are the four main extraembryonic membranes?

The four main extraembryonic membranes are the amnion, yolk sac, allantois, and chorion. Each plays a distinct role in supporting and protecting the developing embryo.

What is the function of the amnion?

The amnion forms the amniotic sac, which is filled with amniotic fluid. It provides a protective cushion for the embryo and eventually fuses with the chorion.

What clinical conditions are associated with the amnion?

Key clinical conditions include amniocentesis for genetic testing, oligohydramnios (low fluid), and polyhydramnios (excess fluid), often caused by developmental defects.

What is the role of the yolk sac in embryonic development?

The yolk sac is involved in early hematopoiesis (blood cell formation), the origin of germ cells, and contributes to gut formation. It connects to the embryo via the vitellointestinal duct.

What is Meckel's diverticulum?

Meckel's diverticulum is a clinical condition resulting from the persistence of the vitellointestinal duct of the yolk sac. It forms a small pouch on the ileum.

What does the allantois develop into after birth?

The allantois becomes the median umbilical ligament postnatally. During development, it contributes to the formation of the urinary bladder.

What are urachal anomalies?

Urachal anomalies occur when the urachus (derived from the allantois) fails to close properly after birth. This can lead to conditions like urachal cysts, sinuses, or fistulas.

What is the difference between chorion laeve and chorion frondosum?

Chorion laeve is the smooth part of the chorion near the decidua capsularis, while chorion frondosum is the villous part near the decidua basalis that contributes to placental development.

Extraembryonic Membranes – Amnion, Chorion & Yolk Sac

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