Embryology Chapter: Nervous System Development
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Questions and Answers

What is the most common risk factor associated with spina bifida?

  • Folate deficiency (correct)
  • Exposure to high altitudes
  • Viral infections
  • Alcohol consumption during pregnancy

    • What is the primary method of transmission for the Zika virus?

  • Contaminated water sources
  • Airborne particles
  • Aedes aegypti mosquito bites (correct)
  • Direct contact with infected individuals

    • Which form of spina bifida is considered the most severe?

  • Encephalocele
  • Myelomeningocele (correct)
  • Meningocele
  • Spina bifida occulta

    • During the Zika virus epidemic, what significant issue was linked to the infection during pregnancy?

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

    What is the current understanding of the cause of spina bifida?

    <p>A combination of genetic and environmental factors (B)</p> Signup and view all the answers

    What is the primary result of neurulation during embryonic development?

    <p>Transformation of the neural plate into the neural tube (D)</p> Signup and view all the answers

    At what point in embryonic development does the process of neurulation initiate?

    <p>Third week (D)</p> Signup and view all the answers

    Which of the following describes the tissue that forms the central and peripheral nervous systems?

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

    What characterizes the transformation of the ectoderm during neural induction?

    <p>Development of the neural plate (A)</p> Signup and view all the answers

    What is a significant structural change that occurs as the primitive streak regresses?

    <p>The trailing behind of the notochord (B)</p> Signup and view all the answers

    What is the primary role of chordamesoderm during gastrulation?

    <p>To develop into the notochord (A)</p> Signup and view all the answers

    What process occurs to the chordamesoderm as the primitive streak regresses?

    <p>It transforms into the notochord (C)</p> Signup and view all the answers

    What is the significance of the notochord during neural induction?

    <p>It prevents the formation of the epidermis (D)</p> Signup and view all the answers

    What cellular structure changes shape during neurulation to form bottle cells?

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

    What is the outcome if microtubule formation is inhibited during neurulation?

    <p>Bottle cells do not form correctly (B)</p> Signup and view all the answers

    What happens to the anterior and posterior neuropores during neural tube formation?

    <p>Anterior closes first (C)</p> Signup and view all the answers

    What condition results from the failure of anterior neuropore closure?

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

    What is the effect of Noggin and Chordin during neural plate formation?

    <p>Suppress epidermal fate (D)</p> Signup and view all the answers

    Which structure originates from the neural tube during development?

    <p>Neural crest cells (D)</p> Signup and view all the answers

    What molecular event blocks the induction of epidermal fate during the formation of the neural plate?

    <p>Inhibition of BMP-4 by Noggin and Chordin (B)</p> Signup and view all the answers

    Which agent disrupts actin microfilaments during neurulation?

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

    What is the result of the improper closure of the posterior neuropore?

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

    What are neural folds responsible for during the neurulation process?

    <p>They produce the neural groove (D)</p> Signup and view all the answers

    What structure changes to form the neural tube?

    <p>Neural ectoderm curling (B)</p> Signup and view all the answers

    Flashcards

    Spina Bifida Occulta

    The mildest form of spina bifida with a small gap in the spine bones.

    Spina Bifida Aperta

    An open form of spina bifida, includes meningocele and myelomeningocele.

    Folate Deficiency

    Insufficient folate can increase the risk of spina bifida.

    Zika Virus Epidemic

    An outbreak starting in April 2015, spread by mosquitoes, linked to microcephaly.

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    Microcephaly

    A birth defect causing smaller than expected head size, potentially from Zika infection.

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    Neural Plate

    A thickened region of the ectoderm that forms the neural tube.

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    Neuroectoderm

    The embryonic tissue that forms the central and peripheral nervous systems.

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    Induction

    The process by which one group of cells influences the development of another.

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    Neural Tube

    A structure formed during embryonic development that gives rise to the central nervous system.

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    Neurulation

    Transformation of the neural plate into the neural tube marking the beginning of the CNS.

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    Germ Layers

    Three layers formed at the end of gastrulation: ectoderm, mesoderm, endoderm.

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    Chordamesoderm

    Mesodermal tissue that forms the future notochord during gastrulation.

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    Notochord

    Structure formed from chordamesoderm, providing support and inducing the nervous system.

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    Neural Induction

    Process where ectoderm is determined to become neural tissue by signals from chordamesoderm.

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    Neural Crest Cells

    Cells that migrate from the neural tube to form various structures in the body.

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    Bottle Cells

    Cells that become bottle-shaped during neurulation, facilitating the tube formation.

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    Anterior Neuropore

    Opening at the front end of the neural tube that closes during development.

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    Posterior Neuropore

    Opening at the rear end of the neural tube that also closes during development.

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    Neural Tube Defects

    Congenital abnormalities due to improper closure of the neural tube.

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    Anencephaly

    Condition caused by failure of anterior neuropore closure, leading to missing parts of the brain.

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    Spina Bifida

    Condition caused by failure of posterior neuropore closure, affecting spinal development.

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    Noggin and Chordin

    Proteins that block BMP-4 to enable neural plate formation.

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    Study Notes

    Embryonic Development of the Nervous System

    • Neural Plate: A thickened region of the ectoderm, precursor to the neural tube which forms the CNS.
    • Neuroectoderm: The embryonic tissue giving rise to the nervous system (both CNS and PNS)
    • Induction: A process where one group of cells influences another's development through signaling molecules.
    • Neural Tube: The structure arising from the neural plate which forms the brain and spinal cord (CNS).
    • Neurulation: The transformation of the neural plate into a neural tube; starts CNS development and indirectly impacts Peripheral Nervous System (PNS) formation. Initiated around week 3.

    Primitive Streak Regression

    • The primitive streak, a structure involved in gastrulation, gradually regresses during neurulation.
    • As the streak moves cranially, it leaves a trail of notochordal precursor cells behind.
    • The regression process creates the neural plate from the ectoderm.
    • The ectoderm now differentiates into surface ectoderm and neural ectoderm.

    Neural Induction

    • Chordamesoderm, a mesodermal precursor of the notochord, is key to neural induction.
    • Signaling molecules from the chordamesoderm influence the ectoderm, causing it to become a neural ectoderm and form the neural plate.
    • Critical aspects include influencing the ectoderm to adopt a "neural fate" and inhibiting epidermal development.
    • Signaling molecules like Noggin and Chordin regulate this process by inhibiting BMP-4, crucial for development pathways.

    Neurulation Events

    • Neural Groove and Folds: The neural plate begins to develop a groove, which then folds to create neural folds, important steps in the neurulation process.
    • Tube Formation: Neural folds meet together and fuse to generate the neural tube; which overlies the ectoderm.
    • Neural Crest Cells: During neural tube formation, neural crest cells, which contribute to the PNS, develop.
    • Neuropore Closure: The neural tube closes in two places- Anterior and Posterior neuropores.
    • Molecular Mechanisms: Molecular signals from the notochord guide the formation and closure of the neural tube.

    Impact of Cell Structure

    • Bottle Cells: These cells exhibit specific cytoskeletal characteristics (microfilaments and microtubules) essential for the tube formation process; particularly during the neurulation stage
      • disruption of either microfilaments or microtubules will interrupt neurulation.
    • Inhibitors (e.g., Colchicine and Cytochalasin D): Disrupting cell cytoskeletons, for example via specific drugs, can affect neurulation.

    Neural Tube Defects

    • Errors in Closure: Defects in the closure of the neural tube lead to a variety of severe birth defects, including anencephaly and spina bifida.
    • Anencephaly: Failure of the anterior neuropore to close, resulting in severe brain malformation. Usually leading to death prior to birth or shortly after.
    • Spina Bifida: Failure of the posterior neuropore to close; varying in severity, from occulta to more serious forms like myelomeningocele, affecting the spinal cord.
    • Risk Factors: Folate deficiency, genetics, and other environmental factors can increase the risk of neural tube defects.
    • Treatment & Prevention: Treatment options (surgical) exist and prevention through sufficient folic acid intake is crucial.

    Zika Virus and Congenital Defects

    • Zika Virus: The Zika virus, spread by mosquitoes, can be passed from pregnant women to their fetuses.
    • Microcephaly: A significant association between Zika virus infection and microcephaly– a birth defect characterized by a smaller than normal head size and possible brain damage in babies.

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    Description

    Explore the intricate processes involved in the embryonic development of the nervous system. This quiz covers key concepts such as the neural plate, neuroectoderm, induction, and neurulation. Test your understanding of how these processes contribute to the formation of the central and peripheral nervous systems.

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