Placenta part 2 - Structure & Changes in Placental Membrane - Endovascular invasion - 3D tour

Summary

In this detailed lecture, Dr. Azaz from MedicalVisual.com explains the structure of the placenta. Beginning with the developmental aspects, the video explores the placental anatomy, including villi, trophoblast layers, and maternal blood vessel interactions. Dr. Azaz covers the function of various placental components, such as the cytotrophoblast and syncytiotrophoblast, in nutrient and waste exchange between mother and fetus. The process of spiral artery remodeling and the importance of a functional placenta are also discussed. The lecture concludes with an explanation of preeclampsia and eclampsia, emphasizing their relation to placental health.

Takeaways

• 😀 The placenta is connected to the fetus via the umbilical cord, allowing the exchange of materials between maternal and fetal blood.
• 😀 Maternal blood flows into the lacunae, and the fetal blood circulates through the villi in the placenta for nutrient and waste exchange.
• 😀 The placenta consists of multiple villi structures, including anchoring villi that stabilize the connection between the fetus and the maternal tissue.
• 😀 The placental membrane, initially thick, becomes thinner over time to facilitate more efficient material exchange between maternal and fetal blood.
• 😀 Cytotrophoblast cells invade maternal blood vessels, remodeling them to increase blood flow to the placenta and reduce resistance.
• 😀 Inadequate remodeling of spiral arteries can lead to fetal hypoxia, which can trigger the release of chemicals to raise maternal blood pressure, resulting in preeclampsia.
• 😀 The placenta undergoes structural changes, including thinning of the syncytiotrophoblast and cytotrophoblast layers, enhancing nutrient and waste exchange.
• 😀 Maternal blood directly contacts the chorionic villi in a hemochorial placenta, which is typical of the human placenta.
• 😀 The cytotrophoblast plays a crucial role in anchoring and maintaining the structure of the placenta, especially in the trophoblastic column.
• 😀 The placenta divides into 15-25 cotyledons, giving it a characteristic cobblestone appearance. These cotyledons consist of branched villi and spiral arteries.
• 😀 Pre-eclampsia, resulting from improper vascular remodeling, is characterized by high maternal blood pressure, proteinuria, and fetal hypoxia. If it progresses to eclampsia, it can lead to seizures.

Q & A

What is the role of the umbilical cord in the structure of the placenta?

The umbilical cord connects the fetus to the placenta, allowing the flow of fetal blood through the umbilical arteries into the placenta, where material exchange occurs. Oxygenated and nutritious blood then flows back to the fetus through the umbilical veins.

What is the primary function of the placenta?

The primary function of the placenta is to facilitate the exchange of materials between the maternal and fetal blood, including oxygen, nutrients, and waste products. This process occurs within the placental membranes.

What are the two types of villi in the placenta, and how do they function?

The two types of villi are anchoring villi and free villi. Anchoring villi secure the placenta to the maternal endometrium, while free villi absorb nutrients from maternal blood.

How does the placenta maintain its structure and prevent degeneration of villi?

The trophoblastic column, formed by the cytotrophoblasts, anchors the villi to the maternal endometrium and prevents them from degenerating. This column ensures that the villi remain intact and functional.

What happens to the placental membrane during pregnancy?

As pregnancy progresses, the placental membrane thins out to become more efficient in material exchange. The thick cytotrophoblast layer degenerates, the mesenchymal core is attenuated, and the fetal blood vessels come closer to the maternal blood.

What are vascular syncytial membranes, and why are they important?

Vascular syncytial membranes are parts of the placental membrane where the endothelium of fetal blood vessels directly contacts the syncytiotrophoblast. These areas are the primary sites for the exchange of materials between the fetal and maternal blood.

What role do cytotrophoblast cells play in remodeling maternal blood vessels?

Cytotrophoblast cells invade maternal spiral arteries, converting them into larger-caliber, low-resistance vessels. This remodeling improves blood flow to the intervillous spaces, ensuring proper oxygen and nutrient supply to the fetus.

What is preeclampsia, and how is it related to the placenta?

Preeclampsia is a condition characterized by fetal hypoxia, high maternal blood pressure, and proteinuria. It can occur if the remodeling of maternal blood vessels is insufficient, leading to poor blood flow to the placenta and a stressed fetal response that raises the mother's blood pressure.

How does the fetus react to insufficient oxygen supply, and what chemicals are involved?

The fetus, experiencing hypoxia, releases chemicals like sFLT-1 that aim to increase the mother's blood pressure in an effort to improve placental blood flow and oxygen supply.

What is the significance of the outer trophoblastic column in placental structure?

The outer trophoblastic column helps anchor the fetal and maternal parts of the placenta, ensuring the placenta remains intact. It also prevents the disintegration of the villi and maintains the overall structural integrity of the placenta.