Embryology 6: Placenta & Membranes MCQ
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Questions and Answers

What is the significance of the invasion of cytotrophoblast cells into spiral arteries?

  • It leads to high pressure blood flow from the maternal side.
  • It allows for low pressure and high volume blood flow. (correct)
  • It decreases the amount of maternal blood available to the placenta.
  • It prevents maternal blood from entering the intervillous spaces.

What condition may develop as a direct result of inadequate transformation of maternal vessels by cytotrophoblast cells?

  • Thromboembolic disease
  • Preeclampsia (correct)
  • Gestational diabetes
  • Eclampsia

Which statement describes the placental barrier before the 5th month of pregnancy?

  • It does not provide any barrier between maternal and fetal blood.
  • It consists only of syncytiotrophoblast cells.
  • It is made up of maternal blood vessels only.
  • It includes endothelium, cytotrophoblast, and syncytiotrophoblast. (correct)

What happens to the placental barrier after the 5th month of pregnancy?

<p>It becomes thinner with fewer cell layers. (A)</p> Signup and view all the answers

What is a hallmark of gestational trophoblastic neoplasia?

<p>Excessive proliferation and invasion by cytotrophoblast cells. (D)</p> Signup and view all the answers

What is the primary role of human chorionic somatotropin produced by the placenta?

<p>To regulate maternal metabolism of glucose (A)</p> Signup and view all the answers

Which of the following is NOT a component of the TORCH complex that can cross the placenta?

<p>Ebola virus (B)</p> Signup and view all the answers

What hormone does the placenta predominantly produce by the second trimester?

<p>Estrogens and progesterone (D)</p> Signup and view all the answers

How does the placenta prevent maternal rejection of the embryo?

<p>By lacking MHC in syncytiotrophoblast and villus cytotrophoblast (D)</p> Signup and view all the answers

What plays a significant role in hormone production by the placenta during the 3rd trimester?

<p>Fetal adrenal glands (D)</p> Signup and view all the answers

What is the function of the decidua basalis during pregnancy?

<p>It serves as the interface between the implanted embryo and the myometrium. (D)</p> Signup and view all the answers

At what point does the decidua capsularis begin to degenerate during pregnancy?

<p>At the third month of pregnancy. (C)</p> Signup and view all the answers

Which statement accurately describes the chorion frondosum?

<p>It develops on the side of the decidua basalis. (D)</p> Signup and view all the answers

What happens to the amnion and chorion during pregnancy?

<p>They fuse together to form the amniochorionic membrane which eventually fuses with the decidua parietalis. (A)</p> Signup and view all the answers

Which of the following correctly describes the decidua parietalis?

<p>It has no direct relation to the embryo. (B)</p> Signup and view all the answers

What is the primary role of the placenta in the relationship between the embryo and mother?

<p>Facilitates the exchange of oxygen, nutrients, and waste (B)</p> Signup and view all the answers

Which statement correctly describes the origin of the amnion?

<p>It develops from the inner cell mass. (D)</p> Signup and view all the answers

What is one of the major functions of the amniotic sac?

<p>Buffers against mechanical injury in a liquid environment (D)</p> Signup and view all the answers

How does the composition of amniotic fluid change by the 11th week of gestation?

<p>It transitions to being predominantly made up of fetal urine. (D)</p> Signup and view all the answers

What property of the amniotic membrane contributes to its use in wound healing?

<p>High concentrations of cytokines and essential growth factors (D)</p> Signup and view all the answers

Which of the following statements accurately describes a characteristic of amniotic fluid?

<p>It increases in volume as the embryo grows. (A)</p> Signup and view all the answers

Why is the amniotic membrane considered non-immunogenic?

<p>It contains no cellular machinery to provoke an immune response. (D)</p> Signup and view all the answers

What is the main purpose of the chorion in relation to the embryo?

<p>To mediate communication and nutrient exchange with the mother (D)</p> Signup and view all the answers

What condition is often associated with defects of the caudal part of the neural tube?

<p>Polyhydramnios (C)</p> Signup and view all the answers

What complication can occur due to polyhydramnios related to the uterine wall?

<p>Premature rupture of membranes (B)</p> Signup and view all the answers

What can happen if an amniotic band constricts a part of the fetus's body?

<p>Necrosis of the constricted area (D)</p> Signup and view all the answers

Which nutrient is not absorbed through histiotrophic nutrition from the yolk sac?

<p>Vitamin C (D)</p> Signup and view all the answers

What is the consequence of the yolk sac ceasing to function as a source of nutrition?

<p>Start of placental function (A)</p> Signup and view all the answers

What potential risk is associated with fetal malposition due to polyhydramnios?

<p>Umbilical cord prolapse (C)</p> Signup and view all the answers

Which of the following is NOT a complication of polyhydramnios?

<p>Fetal weight loss (D)</p> Signup and view all the answers

What structure is incorporated into the body of the embryo during its folding?

<p>Yolk sac (C)</p> Signup and view all the answers

What condition is characterized by umbilical blood vessels running over or in close proximity to the cervical os?

<p>Vasa previa (D)</p> Signup and view all the answers

Which type of hydatiform mole has a 2% risk of evolving into choriocarcinoma?

<p>Complete mole (B)</p> Signup and view all the answers

What is a potential serious consequence of a placental abruption during the third trimester?

<p>Maternal shock and fetal distress (C)</p> Signup and view all the answers

What distinguishes dizygotic twins from monozygotic twins?

<p>Dizygotic twins develop from two separate oocytes (D)</p> Signup and view all the answers

What can excessive production of hCG from a hydatiform mole cause?

<p>Hyperthyroidism and hyperemesis (A)</p> Signup and view all the answers

Which condition involves carcinoma of the trophoblast potentially spreading to other organs?

<p>Choriocarcinoma (A)</p> Signup and view all the answers

What complication can arise from twinning due to blood vessel anastomosis between embryos?

<p>Congestive heart failure (A)</p> Signup and view all the answers

In a partial mole, what is commonly present that differentiates it from a complete mole?

<p>Presence of fetal tissue (C)</p> Signup and view all the answers

Flashcards

Cytotrophoblast Invasion

Cytotrophoblast cells, a type of placental cell, invade and transform maternal spiral arteries. This process is crucial for efficient blood flow to the placenta.

Placental Perfusion

The process of blood flow through the placenta, allowing for exchange of nutrients and oxygen between mother and fetus.

Preeclampsia

A serious pregnancy complication characterized by high blood pressure, often related to insufficient blood flow to the placenta due to inadequate cytotrophoblast invasion.

Placental Barrier

A barrier separating fetal and maternal blood, composed of different layers of cells. It allows for nutrient and oxygen exchange while preventing direct mixing of blood.

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Intervillous Spaces

Spaces within the placenta where maternal blood flows, bathing the villi and facilitating exchanges between mother and fetus.

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Decidua Basalis

The region of the decidua between the implanted embryo and the myometrium. It's where the chorion frondosum develops.

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Decidua Capsularis

The region of the decidua that overlies the embryo and its chorionic cavity. It degenerates by the 3rd month of pregnancy.

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Decidua Parietalis

The rest of the decidua, not directly associated with the implanted embryo.

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Chorion Frondosum

The part of the chorion that faces the decidua basalis. It's involved in gas exchange and nutrient transfer.

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Amniochorionic membrane

The fusion of the amnion and chorion. It will later fuse with the decidua parietalis.

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Polyhydramnions

Excessive amniotic fluid in the amniotic sac during pregnancy.

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Fetal Factors of Polyhydramnions

Conditions in the fetus that can lead to polyhydramnions. Examples include: oesophageal or duodenal atresia, anencephaly, infections, or congenital diaphragmatic hernia.

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Amniotic Bands

Fibrous strands that form within the amniotic sac, potentially causing constrictions and malformations in the developing fetus.

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Yolk Sac

A sac connected to the embryo, initially serving as the major source of nutrition. Later, it becomes incorporated into the body of the embryo.

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Histiotrophic Nutrition

Type of nutrition where the embryo absorbs nutrients directly through its tissues by endocytosis.

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Vitelline Sac

The yolk sac, which becomes incorporated into the embryo during development, contributing to the formation of the gut.

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Preterm Contractions (Polyhydramnions)

Early contractions of the uterine wall due to excessive amniotic fluid, potentially leading to preterm labor.

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Umbilical Cord Prolapse

The umbilical cord descends into the birth canal ahead of the baby, potentially causing a life-threatening situation.

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Parasitic Relationship

The embryo needs to obtain oxygen, nutrients, and eliminate waste from the mother. The placenta and extraembryonic membranes mediate this communication.

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Placenta Origin

The placenta and chorion develop from the trophoblast, a layer of cells surrounding the embryo.

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Amniotic Sac

A fluid-filled sac that envelops the developing embryo, providing protection and allowing for growth and movement.

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Functions of the Amniotic Sac

Mechanical injury protection, allows for movement and growth, facilitates fetal lung development, prevents adhesion to the chorionic cavity, acts as a barrier to infections, maintains temperature, and regulates fluids/electrolytes.

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Amniotic Membrane Uses

Used to cover wounds and burns due to their anti-inflammatory and anti-angiogenic properties. Also used in ophthalmic surgeries to restore the cornea.

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Amniotic Membrane Stem Cells

Contains stem cells which are the focus of research for their regenerative potential.

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Amniotic Fluid Composition (Early vs. Late)

Before the 11th week, amniotic fluid is formed by diffusion of maternal plasma from the chorion to the amniotic membrane. After the 11th week, fetal urine becomes the primary source of amniotic fluid.

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Fetal Urine Differences

Fetal urine doesn't contain wastes because those are secreted through the placenta.

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Abrupt Placentae

A premature separation of the placenta from the uterine wall during the third trimester, causing painful bleeding.

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Vasa Previa

A condition where umbilical blood vessels run over or near the cervical opening, causing painless vaginal bleeding and fetal bradycardia.

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Choriocarcinoma

A type of cancer that develops in the trophoblast (cells that form the placenta) during pregnancy.

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Hydatiform Mole

An abnormal growth of the placental tissue, characterized by grape-like clusters.

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Dizygotic Twins

Two separate eggs are fertilized by two different sperm, leading to two embryos.

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Monozygotic Twins

One egg is fertilized by one sperm, and the resulting embryo splits into two identical twins.

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Anastomosis

A connection between the blood vessels of twins, allowing for blood exchange.

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Twin-Twin Transfusion Syndrome

A condition where one twin receives more blood than the other, potentially causing heart failure or death in the receiving twin.

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Passive Immunity in Fetus

Antibodies from the mother's blood cross the placenta, providing the fetus with temporary immunity against infections.

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TORCH Infections

A group of infectious agents (Toxoplasma gondii, Other, Rubella, Cytomegalovirus, Herpes) that can cross the placenta and harm the fetus.

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Placenta's Endocrine Role

The placenta produces hormones like hCG, estrogen, and progesterone, playing a crucial role in maintaining pregnancy.

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Human Chorionic Somatotropin (hCS)

A hormone produced by the placenta that regulates maternal metabolism of glucose and prepares the body for lactation.

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Placenta Prevents Rejection

The placenta lacks MHC markers, which are responsible for immune recognition, preventing the mother's immune system from rejecting the fetus.

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Study Notes

Extraembryonic Membranes

  • The embryo establishes a parasitic relationship with the mother for oxygen, nutrients, and waste elimination.
  • The embryo must avoid rejection as a foreign body.
  • The placenta and extraembryonic membranes facilitate communication with the mother.
  • The placenta arises from the trophoblast.
  • The amnion, yolk sac, allantois, and extraembryonic mesoderm derive from the inner cell mass.

Amniotic Membrane and Cavity

  • The amniotic membrane encloses the embryo completely.
  • Functions of the amniotic sac:
    • Cushioning against mechanical injury.
    • Accommodating growth.
    • Allowing fetal movement.
    • Protecting the fetus from adherence to the chorionic wall.
    • Acting as a barrier to infections.
    • Maintaining a consistent temperature.
    • Maintaining homeostasis of fluids and electrolytes.
  • Amniotic membranes can be used in treating wounds and burns.
  • They show anti-inflammatory and anti-angiogenic properties.
  • Used in ophthalmic surgery (cornea restoration).
  • Stem cells within amniotic membranes are a research focus.

Amniotic Membrane Functions

  • Contains significant cytokines and growth factors.
  • Reduces pain when applied to wounds.
  • Increases wound healing.
  • Has antibacterial properties.
  • Is not immunogenic (no foreign material identification).
  • Acts as a biological barrier.
  • Supports cell migration and proliferation.
  • Reduces inflammation.
  • Reduces scar tissue formation.

Amniotic Fluid Composition

  • Amniotic fluid composition changes significantly (and is different to adult urine).
  • Primarily urine of the embryo, starting in the 11th week.
  • Fetal urine lacks waste products, as these are excreted through the placenta.
  • Lung secretions are also released into the amniotic fluid.

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Embryology 6 - Placenta and Membranes PDF

Description

Explore the crucial roles of extraembryonic membranes, including the placenta and amniotic sac, in supporting embryonic development. This quiz covers the relationship between the embryo and mother, as well as the functions of the amniotic membrane in protecting and nurturing the fetus. Test your knowledge on these essential biological structures.

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