EMBRYOLOGY-4
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Questions and Answers

What is the condition that may develop from silent remnants of the notochord?

  • Chordomas (correct)
  • Somites
  • Mesenchyme
  • Intrambryonic coelom

    • What major structure is formed from the paraxial mesoderm in the trunk region of the embryo?

  • Kidneys
  • Somites (correct)
  • Heart
  • Amniotic sac

    • Which type of mesoderm originates from the intermediate mesoderm?

  • Gonads (correct)
  • Skull
  • Neural plate
  • Somatic mesoderm

    • Which of the following mesoderm layers separates into splanchnic and somatic mesoderm?

    <p>Lateral plate mesoderm</p> Signup and view all the answers

    Which embryonic structure is formed by the migration of cells rostral to the oropharyngeal membrane?

    <p>Primordial heart field</p> Signup and view all the answers

    What is the result of separating the lateral plate mesoderm into splanchnic and somatic mesoderm?

    <p>Formation of the intrambryonic coelom</p> Signup and view all the answers

    Which structure is formed as a result of the thickening of ectodermal cells during neurulation?

    <p>Neural tube</p> Signup and view all the answers

    Symptoms associated with chordomas may develop due to compression of which structures?

    <p>Neural tissue</p> Signup and view all the answers

    What type of cells does the neural crest give rise to after its formation?

    <p>Melanocytes and peripheral nervous system cells</p> Signup and view all the answers

    In the head region of the embryo, which structure develops from the paraxial mesoderm?

    <p>Head mesenchyme</p> Signup and view all the answers

    Which signaling structures influence the ectoderm to differentiate into the neural crest?

    <p>Notochord and prechordal plate</p> Signup and view all the answers

    During which developmental process does the neural groove form?

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

    What is the fate of the neural tube after the neural crest has formed?

    <p>It will become central nervous tissue.</p> Signup and view all the answers

    Which of the following is NOT a derivative of the neural crest?

    <p>Skeletal muscles</p> Signup and view all the answers

    How does the neural tube formation occur?

    <p>The neural groove deepens, and edges rise to join.</p> Signup and view all the answers

    What can be classified as a 'fourth germinal layer' in embryonic development?

    <p>Neural crest</p> Signup and view all the answers

    What process leads to the formation of the three germinal layers during embryonic development?

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

    Which of the following layers is not one of the three germinal layers formed during gastrulation?

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

    What structure marks the beginning of gastrulation in the embryo?

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

    Which factor is known to guide the migration of epiblast cells during the formation of the primitive streak?

    <p>FGF 8</p> Signup and view all the answers

    What is primarily formed by secondary neurulation?

    <p>The caudal part of the neural tube and caudal somites</p> Signup and view all the answers

    What can remnants of the primitive streak develop into?

    <p>Sacrococcygeal teratomas</p> Signup and view all the answers

    What condition involves the fusion of legs in developing embryos and may also affect internal organs?

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

    Which of the following best describes situs inversus?

    <p>Organs positioned on the opposite side of the body</p> Signup and view all the answers

    Which genes play a crucial role in controlling rostrocaudal patterning?

    <p>Hox genes</p> Signup and view all the answers

    What induces the dorso-ventral organization in the embryo?

    <p>Unequal concentration of morphogens in the mesoderm</p> Signup and view all the answers

    The embryonic disk is transformed during gastrulation into how many germinal layers?

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

    Which term describes twins that are not completely separated at certain parts of the body?

    <p>Conjoined twins</p> Signup and view all the answers

    At what stage does the pluripotency of embryonic cells primarily decrease?

    <p>As cells start specialization pathways</p> Signup and view all the answers

    How does the embryo establish its rostrocaudal axis?

    <p>With the formation of the primitive streak in the caudal part</p> Signup and view all the answers

    What role do Hox genes play in embryonic development?

    <p>They activate and repress other developmental genes</p> Signup and view all the answers

    Which of the following reflects a key concept regarding the symmetry of the embryo?

    <p>Some organs are more developed on the right than the left</p> Signup and view all the answers

    Which structure does the primitive endoderm primarily form?

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

    What is the primary function of the mesoderm?

    <p>Subdividing into compartments for organ development</p> Signup and view all the answers

    Which of the following is NOT a structure developed from the endoderm?

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

    What will the cloacal membrane become?

    <p>Anal canal and urinary tract</p> Signup and view all the answers

    Which component of the mesoderm is responsible for forming the ribs?

    <p>Paraxial mesoderm</p> Signup and view all the answers

    What is characterized by a lack of mesodermal spread?

    <p>Oropharyngeal and cloacal membranes</p> Signup and view all the answers

    Which of the following is a subdivision of mesoderm involved in cardiac formation?

    <p>Lateral mesoderm</p> Signup and view all the answers

    The prechordal plate is associated with which structure?

    <p>Anterior visceral endoderm</p> Signup and view all the answers

    What role does the factor Snail play in the process of EMT?

    <p>It represses factors that maintain epithelial characteristics.</p> Signup and view all the answers

    During which wave of migration is the definitive endoderm created?

    <p>First wave of migration.</p> Signup and view all the answers

    Which of the following is TRUE regarding mesenchymal cells?

    <p>They are multipotent stem cells capable of developing into connective tissue cells.</p> Signup and view all the answers

    What is the fluid environment that facilitates cell migration composed of?

    <p>Primarily hyaluronic acid.</p> Signup and view all the answers

    What happens to cells when Snail is activated in malignancy?

    <p>Cells proliferate and break through the basement membrane.</p> Signup and view all the answers

    What structures are directly repressed by the action of Snail?

    <p>Cell membrane proteins critical for cell-to-cell adhesion.</p> Signup and view all the answers

    Which layer of the embryo is the first to develop?

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

    What type of connective tissue does mesenchymal cells give rise to?

    <p>Connective tissue such as bone and cartilage.</p> Signup and view all the answers

    Study Notes

    Embryonic Development

    • Gastrulation: The process of the 2-layered embryo forming 3 layers (endoderm, mesoderm, ectoderm) during the 3rd and 4th week of development.
    • Germ Layers: These layers form different tissues.
    • Endoderm: Forms the internal layer of the embryo.
    • Mesoderm: Forms the middle layer of the embryo
    • Ectoderm: Forms the external layer of the embryo.
    • Clinical Disorders: Certain conditions can arise during gastrulation.
    • Sirenomelia: Babies with fused legs and sometimes fused internal organs
    • Conjoined twins: Twins not separated in certain parts of the body
    • Situs inversus: Organs in the opposite positions they should be.

    Formation of Layers

    • Primitive streak: Marks the beginning of gastrulation. It's an invagination on the dorsal pole of the embryo, which has a primitive node and groove.
    • Cell migration: Cells from the epiblast migrate toward the primitive streak region.
    • Node and pit: Sections of the primitive streak that form as part of the process.
    • Formation of the primitive streak: Epiblast cells dedifferentiate and migrate, moving toward the primitive streak location. This is possible due to factors such as FGF8. This involves epithelio-mesenchymal transitions (EMT)

    Mesoderm Formation

    • Subdivisions: The mesoderm is divided in parts.
    • Prechordal plate: Group of cells that will form part of the head. Influences head and nervous system development.
    • Notochord: Elongates rostrally from the primitive node, important for the development of structures such as axial skeletal and neural tissues.
    • Paraxial mesoderm: Develops on either side of the notochord
    • Intermediate mesoderm: Develops on both sides of the paraxial mesoderm
    • Lateral Plate Mesoderm: Lies lateral to the intermediate mesoderm.
    • Extraembryonic mesoderm: Continuous with intraembryonic mesoderm
    • Heart field: Forms on the rostral part of the oropharyngeal membrane

    Ectoderm Derivatives

    • Neural crest: Structure that results from cells migrating from ectoderm. Will form peripheral nervous system, melanocytes and other structures.
    • Neural plate: The structure where neural crest cells originate.
    • Neural tube: Formed from the neural plate invagination.
    • Neurogenesis: Process where neurons are created from neural cells
    • Neural crest cells: These cells form important structures including the Peripheral Nervous System (PNS), melanocytes, and components of the head.

    Primitive Streak Remnants

    • Chordomas: Cancers that develop from notochord remnants.
    • Teratomas: Abnormal growths that can develop from primitive streak remnants.

    Symmetry and Situs inversus

    • Cilia: Structures in the embryo that influence left-right asymmetry.
    • Left-Right patterning: The process of establishing left/right symmetry in the developing embryo.
    • Role of molecules: FGF8, Nodal and Lefty molecules are crucial in establishing left-right patterning.
    • Kartagener Syndrome: A condition where cilia cannot move, associated with situs inversus
    • Situs inversus totalis: Complete inversion of organs

    Other Important Factors

    • Teratogens: Substances that can cause birth defects, such as alcohol and specific genes
    • Sonic hedgehog pathway: Involved in development and communication between cells, also involved in the development of the brain
    • Ciliopathies: A group of diseases related to cilia dysfunction.

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    Related Documents

    Embryology 4 - Gastrulation PDF

    Description

    Test your knowledge on the embryological development of mesoderm structures and their derivatives. This quiz covers key concepts related to the notochord, paraxial mesoderm, and the neural crest formation. Perfect for students studying developmental biology or embryology.

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