Fetal Membranes: Chorion Structure and Function

The fetal membranes play a critical role in pregnancy, providing structural support and biochemical functions essential for fetal development. The chorion, one of the two fetal membranes, is pivotal in fetal-maternal interactions.

Structure of the Chorion

The chorion is the outermost fetal membrane formed from extraembryonic mesoderm and trophoblast layers. It consists of two layers:

• Chorion laeve: The smooth, nonvillous part of the chorion that lines the uterine cavity.
• Chorion frondosum: The villous chorion, which contributes to the formation of the placenta.

Function of the Chorion

The chorion facilitates critical processes including:

• Gas and Nutrient Exchange: The chorion, in conjunction with the placenta, supports oxygen and nutrient transport to the fetus.
• Hormonal Secretion: It plays a role in the synthesis of essential pregnancy hormones like human chorionic gonadotropin (hCG).
• Immunological Protection: The chorion acts as a selective barrier, protecting the fetus from maternal immune responses.

Clinical Significance

Abnormalities in chorion development can lead to pregnancy complications such as placenta previa, chorioamnionitis, and preterm labor.

Conclusion

Understanding the structure and function of the chorion is vital for obstetricians managing pregnancy and fetal health.