L15. Embryology - Placentation
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Questions and Answers

What percentage of premature births is accounted for by placentation issues?

  • 10%
  • 20%
  • 5%
  • 15% (correct)

    • Which artery is responsible for delivering oxygenated maternal blood to the intervillous space?

  • Umbilical arteries
  • Spiral arteries (correct)
  • Endometrial arteries
  • Uterine veins

    • What drains the blood from the intervillous space in the placental circulation?

  • Endometrial arteries
  • Umbilical vein
  • Uterine veins (correct)
  • Spiral arteries

    • In the context of placental circulation, what does the umbilical cord consist of?

    <p>Two umbilical arteries and one umbilical vein</p> Signup and view all the answers

    Which component is NOT part of the maternal side of placental circulation?

    <p>Umbilical arteries</p> Signup and view all the answers

    What is the primary role of the maternal portion of the placenta?

    <p>To form the decidua basalis</p> Signup and view all the answers

    Which component is primarily responsible for nutrient and gas exchange in the placenta?

    <p>Chorionic Villi</p> Signup and view all the answers

    What structure forms from the fusion of the chorion and the decidua during placentation?

    <p>Complete placenta</p> Signup and view all the answers

    In the context of monozygotic twins, what is the result of their separation after implantation?

    <p>Development of separate placentas</p> Signup and view all the answers

    Which of the following is considered an endocrine function of the placenta?

    <p>Secretion of human chorionic gonadotropin (hCG)</p> Signup and view all the answers

    Which part of the placenta is responsible for the formation of the villous chorion?

    <p>Syncytiotrophoblast</p> Signup and view all the answers

    What issue can arise concerning the amniotic fluid balance during early placental development?

    <p>Excess fluid production</p> Signup and view all the answers

    What is the primary change that occurs to cytotrophoblasts during the 2nd trimester?

    <p>They fuse into syncytiotrophoblasts.</p> Signup and view all the answers

    What components make up the placental barrier later in gestation?

    <p>Syncytiotrophoblast and capillary endothelial cells.</p> Signup and view all the answers

    What role do anchoring villi play in placentation?

    <p>They anchor the placenta to the decidua basalis.</p> Signup and view all the answers

    What happens to cytotrophoblasts within anchoring villi?

    <p>They proliferate to form dense columns.</p> Signup and view all the answers

    Which layer acts as the 'floor' of the placenta?

    <p>The decidua basalis.</p> Signup and view all the answers

    How do extravillous trophoblasts contribute to placentation?

    <p>They invade the decidua and remodel uterine arteries.</p> Signup and view all the answers

    In which location is the majority of the fetal cytotrophoblast present?

    <p>In the basal plate.</p> Signup and view all the answers

    What is the significance of the thinning of the placental barrier?

    <p>It enhances maternal blood flow to the fetus.</p> Signup and view all the answers

    What type of tissue is primarily involved in forming the columns of anchoring villi?

    <p>Cytotrophoblasts.</p> Signup and view all the answers

    Which of the following best describes the functional importance of the placental barrier?

    <p>It regulates the transport of nutrients and gases between mother and fetus.</p> Signup and view all the answers

    What is established by the end of week 3 in the development of the placenta?

    <p>Primitive placenta</p> Signup and view all the answers

    Which component of the primitive placenta consists of differentiated endometrium?

    <p>Decidua</p> Signup and view all the answers

    What forms when the capillaries in the tertiary chorionic stem villi fuse?

    <p>Arteriocapillary networks</p> Signup and view all the answers

    Which of the following best describes the embryonic component of the primitive placenta?

    <p>Chorion with developing chorionic villi</p> Signup and view all the answers

    What type of blood flow begins slowly through the capillaries of the tertiary chorionic stem villi?

    <p>Fetal blood</p> Signup and view all the answers

    What role do decidual cells have in the developing placenta?

    <p>Support the developing placenta</p> Signup and view all the answers

    Which structure directly connects the embryonic heart to the developing placenta?

    <p>Extraembryonic somatopleuric mesoderm</p> Signup and view all the answers

    Which of the following statements about the decidua is true?

    <p>It is the site of embryonic implantation</p> Signup and view all the answers

    Which fetal structure is primarily responsible for the exchange of nutrients and waste?

    <p>Chorionic villi</p> Signup and view all the answers

    At week 4 of development, how has the embryo, amniotic cavity, and chorionic cavity changed with respect to the uterine cavity?

    <p>They have only slightly expanded into the uterine cavity.</p> Signup and view all the answers

    What is a notable feature of the implanted embryo at week 4 regarding the placenta?

    <p>The placenta is primitive and not fully formed.</p> Signup and view all the answers

    What is indicated by the term 'decidua' in relation to the week 4 embryo?

    <p>It denotes the uterine endometrium during pregnancy.</p> Signup and view all the answers

    Which of the following statements is accurate for the condition of the embryo at week 4?

    <p>The embryo is still in a formative stage without significant development.</p> Signup and view all the answers

    Which structure is primarily associated with the implantation seen in week 4?

    <p>Primitive placenta.</p> Signup and view all the answers

    Which statement correctly captures the relationship between the implanted embryo and the uterine endometrium at week 4?

    <p>The embryo is partially embedded in the endometrium.</p> Signup and view all the answers

    What happens to the chorionic and amniotic cavities by week 4?

    <p>They are yet to exhibit any growth.</p> Signup and view all the answers

    Which of the following describes the anatomical characteristics of the implanting embryo at week 4?

    <p>It retains a rudimentary form without significant differentiation.</p> Signup and view all the answers

    In which publication is the diagram of the sagittal section of an implanted embryo referenced?

    <p>Medical Embryology by Langman.</p> Signup and view all the answers

    What major milestone in embryonic development is highlighted at week 4?

    <p>Secure implantation within the uterine wall.</p> Signup and view all the answers

    Study Notes

    Placentation Lecture Learning Objectives

    • Describe the formation of the primitive placenta
    • Describe the formation of the lacunar blood network
    • Describe the formation of chorionic villi
    • Describe the formation of the primitive placenta
    • Describe the development of the early placenta
    • Describe the decidua during the first trimester
    • Compare and contrast the three regions of the decidua
    • Describe the chorion during the first trimester
    • Compare and contrast the two regions of the chorion
    • Describe the structure of the placenta at the end of the first trimester
    • Describe the organization and structure of the placenta
    • Describe the fetal portion of the placenta, the villous chorion
    • Describe the maternal portion of the placenta, the decidua basalis
    • Describe the interaction of the chorionic villi with the intervillous space and the basal plate
    • Describe chorionic villi
    • Describe the changes in chorionic villi structure during gestation
    • Describe the placental barrier, where maternal and fetal circulations exchange
    • Describe the components of the basal plate
    • Describe anchoring villi
    • Describe extravillous trophoblasts
    • Describe the role of extravillous trophoblasts in placental structure and pathophysiology
    • Describe the maternal-fetal circulation of the placenta
    • Describe how the placental barrier is crossed by gases, nutrients, waste, antibodies, and drugs
    • Describe the endocrine functions of the placenta
    • Describe the structure and function of the amniotic cavity
    • Describe the structure and function of the amniochorionic membrane
    • Describe the source(s) of amniotic fluid and its flow in the fetus
    • Describe the functions of amniotic fluid
    • Describe the consequences of problems with amniotic fluid balance
    • Describe oligohydramnios, including its cause
    • Describe polyhydramnios, including its cause
    • Describe the appearance of the term placenta
    • Describe the placenta and membranes of twins
    • Describe the placenta of dizygotic twins
    • Describe the placenta of monozygotic twins
    • Describe the placenta of monozygotic twins that separate before blastocyst formation
    • Describe the placenta of monozygotic twins that separate during blastocyst formation
    • Describe the placenta of monozygotic twins that separate after implantation

    Review of the Primitive Placenta

    • Formation of Lacunar Blood Network
    • Formation of Chorionic Villi
    • Formation of Primitive Placenta

    Development of Early Placenta

    • Decidua during the first trimester
    • Chorion during the first trimester
    • Placenta at the end of the first trimester

    Organization and Structure of the Placenta

    • Fetal Portion: Villous Chorion (Chorion Frondosum)
    • Maternal Portion: Decidua Basalis
    • Chorionic Villi (floating or branching villi)
    • Basal Plate and Anchoring Villi
    • Extravillous Trophoblasts
    • Placental Circulation
    • Placental Transport

    Amniotic Cavity

    • Amniochorionic Membrane
    • Amniotic Fluid
    • Functions of Amniotic Fluid
    • Problems with Amniotic Fluid Balance
      • Oligohydramnios
      • Polyhydramnios

    Term Placenta

    • Placenta at Birth
    • Appearance of term placenta
    • Fetal Side of placenta
    • Maternal Side of Placenta

    Placenta and Membranes of Twins

    • Dizygotic Twins (non-identical)
    • Monozygotic Twins (identical)
      • Dizygotic vs Monozygotic

    Additional Notes

    • Implantation site of the embryo in the uterine wall is called the decidua.
    • Three regions of the decidua can be distinguished
      • Decidua Basalis
      • Decidua Capsularis
      • Decidua Parietalis
    • The chorion changes from chorion frondosum to chorion laeve.
    • The primitive placenta develops into the true placenta.
    • Fetal and maternal components form the true placenta.
    • The placental barrier separates maternal and fetal blood. The components of the barrier change as gestation progresses.

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    Related Documents

    Placentation - Rod D. Braun (PDF)

    Description

    This quiz covers the essential learning objectives of placentation, focusing on the formation and structure of the placenta during the first trimester. Explore the development of chorionic villi, the lacunar blood network, and the decidua, while comparing the different regions involved. Test your understanding of the interactions between fetal and maternal tissues in placental formation.

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