Embryonic Development Quiz
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Questions and Answers

Which embryonic tissue contributes to the formation of the ribs?

  • Lateral plate mesoderm only
  • Neural crest cells only
  • Paraxial mesoderm only
  • Both paraxial and lateral plate mesoderm (correct)

    • Which type of tissue is NOT formed from mesenchymal cells during skeletal development?

  • Chondroblasts
  • Myoblasts (correct)
  • Osteoblasts
  • Fibroblasts

    • What type of ossification is involved in the formation of the limb bones?

  • Endochondral ossification (correct)
  • Direct ossification
  • Intramembranous ossification
  • Membranous ossification

    • From which embryonic structure do the vertebrae primarily develop?

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

    What process explains the migration and fusion of sclerotome cells to form the vertebrae?

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

    Which part of the somite gives rise to the muscles associated with the vertebral column?

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

    Which structures are derived from the lateral plate mesoderm?

    <p>Upper and Lower limb bones</p> Signup and view all the answers

    Intramembranous ossification occurs when bone develops directly from:

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

    Which limb defect is characterized by the complete absence of one or more extremities?

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

    An abnormal duplication of which structure is the cause of polydactyly?

    <p>Zone of polarizing activity (ZPA)</p> Signup and view all the answers

    Cleft hand and foot is marked by an unusual split between which metacarpal/metatarsal bones?

    <p>Second and fourth</p> Signup and view all the answers

    Which condition involves congenital joint contractures in more than one joint?

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

    Amniotic bands can cause which type of limb defect?

    <p>Ring constrictions and amputations</p> Signup and view all the answers

    Absence of which muscles and associated digital defects are characteristic of Poland Anomaly?

    <p>Pectoralis minor and partial loss of pectoralis major</p> Signup and view all the answers

    What is a key characteristic of Prune Belly Syndrome?

    <p>Partial or complete absence of abdominal musculature</p> Signup and view all the answers

    Which of the following conditions is often associated with severe lung or kidney problems, and a high mortality rate?

    <p>Prune Belly Syndrome</p> Signup and view all the answers

    Which of the following primarily regulates the patterning of vertebral shapes?

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

    Which structure contributes to the formation of the nucleus pulposus of the intervertebral disc?

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

    The bony portion of each rib is derived from what structure?

    <p>Sclerotome cells in the paraxial mesoderm</p> Signup and view all the answers

    From which germ layer is the sternum primarily developed?

    <p>Parietal layer of lateral plate mesoderm</p> Signup and view all the answers

    Which of the following is a characteristic of spina bifida occulta?

    <p>Defect covered by skin, with no neurological deficits</p> Signup and view all the answers

    What is the key difference between meningocele and myelomeningocele?

    <p>Myelomeningocele involves exposure of neural tissue but meningocele does not.</p> Signup and view all the answers

    From which germ layer do most skeletal muscles originate?

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

    What is the origin of smooth muscles surrounding the gut?

    <p>Splanchnic/visceral lateral plate mesoderm</p> Signup and view all the answers

    Which type of muscle tissue is derived from the somato-pleuric mesoderm?

    <p>Smooth muscle</p> Signup and view all the answers

    What is the role of BMP4, in the molecular regulation of muscle development?

    <p>Signals ventrolateral (VLL) cells to express the muscle-specific gene MyoD</p> Signup and view all the answers

    Where do progenitor muscle cells form to create the dermomyotome?

    <p>Upper region of the somite</p> Signup and view all the answers

    From which region do the limb muscles originate?

    <p>Ventrolateral Lip (VLL) cells</p> Signup and view all the answers

    Which of these is a muscle derived from the remaining myotome cells?

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

    Which structure directs the formation of muscles in the head region?

    <p>Connective tissue elements derived from neural crest cells</p> Signup and view all the answers

    What is the primary difference between somitomeres and somites?

    <p>Somitomeres are only found in the head region, while somites are found from the occipital to the sacral regions</p> Signup and view all the answers

    What is the origin of the skeletal muscles in the trunk?

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

    Which of the following is NOT a derivative of the somites?

    <p>Cardiac muscle</p> Signup and view all the answers

    What is the role of the apical ectodermal ridge (AER) in limb development?

    <p>To maintain an undifferentiated, rapidly proliferating zone in adjacent mesenchyme</p> Signup and view all the answers

    Which cell type is primarily regulated by the serum response factor (SRF)?

    <p>Smooth muscle cells</p> Signup and view all the answers

    What separates the primaxial and abaxial domains?

    <p>The lateral somitic frontier</p> Signup and view all the answers

    From what structure do tendons originate from?

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

    What is the function of SCLERAXIS in tendon development?

    <p>It regulates the expression of genes involved in tendon differentiation.</p> Signup and view all the answers

    During which week of development does rotation of the limbs occur?

    <p>7th week</p> Signup and view all the answers

    What is the primary function of the ventral primary rami of spinal nerves in limb development?

    <p>To provide motor and sensory innervation of limb musculature</p> Signup and view all the answers

    What is the origin of the cartilage in the ribs that attach to the sternum?

    <p>Abaxial sclerotome cells</p> Signup and view all the answers

    What process initiates the formation of a joint cavity?

    <p>Apoptosis of cells in the joint interzone</p> Signup and view all the answers

    What is the role of WNT14 in joint development?

    <p>It acts as an inductive signal for joint positioning</p> Signup and view all the answers

    Which of the following best describes the orientation of the big toe after limb rotation?

    <p>It lies medially</p> Signup and view all the answers

    Which of the following correctly describes the nerve supply of extensor and flexor muscles in the limbs?

    <p>Extensor muscles are innervated by dorsal branches, while flexor muscles are innervated by ventral branches</p> Signup and view all the answers

    What connective tissue plays a role in the development of the complex pattern of muscles in the limbs?

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

    Study Notes

    Musculoskeletal System Development

    • Skeletal System Components: The skeleton is divided into the axial (skull, vertebrae, ribs, sternum) and appendicular (pectoral girdle, pelvic girdle, upper/lower limbs) skeletons.

    • Skeletal Development Sources:

      • Paraxial mesoderm forms the skull, vertebrae, and parts of ribs.
      • Lateral plate mesoderm forms upper/lower limb bones, costal cartilage, and sternum.
      • Neural crest cells contribute to facial and cranial bones.

    • Vertebrae Development:

      • Sclerotome cells from somites (paraxial mesoderm) migrate around the spinal cord and notochord, eventually merging and resegmenting.
      • Resegmentation combines caudal half of one somite with cranial half of the next, forming a vertebra.
      • Myotomes bridge intervertebral discs, enabling spinal movement.

    • Intervertebral Disc Structure: Consists of annulus fibrosus (from sclerotome cells) and nucleus pulposus (from notochord).

    • Rib Development: Bony portion from sclerotome cells, cartilaginous portion from migrating sclerotome cells into lateral plate mesoderm.

    • Sternum Development: Forms from lateral plate mesoderm with two sternal bands fusing to form the sternum (manubrium, sternebrae, xiphoid process).

    Bone Ossification

    • Intramembranous Ossification: Mesenchymal cells directly transform into bone without a cartilage stage.

    • Endochondral Ossification: Most bones develop from hyaline cartilage models that subsequently ossify.

    Vertebral Developmental Defects

    • Spina Bifida: Imperfect fusion of vertebral arches.

      • Spina Bifida Occulta: Minor, bony arch defect, spinal cord intact.
      • Spina Bifida Cystica: Severe, neural tissue exposure.
        • Meningocele: Fluid-filled sac with meninges; spinal cord spared.
        • Myelomeningocele: Fluid-filled sac containing spinal cord and nerve roots.

    • Prenatal screening tools include ultrasound and amniocentesis (alpha-fetoprotein levels).

    Muscular System Development

    • Muscle Types:

      • Skeletal (paraxial mesoderm)
      • Smooth (lateral plate mesoderm)
      • Cardiac (lateral plate mesoderm)

    • Skeletal Muscle Formation: From somites (paraxial mesoderm) and somitomeres (head region).

    • Smooth Muscle Formation: From splanchnic lateral plate mesoderm, with some exceptions from ectoderm (e.g., pupil, mammary, sweat glands).

    • Cardiac Muscle Formation: From splanchnic lateral plate mesoderm surrounding the heart tube.

    • Muscle Formation Regulation: BMP4 and WNT proteins, along with SHH, signal specific muscle groups to express myogenic regulatory factors (MRFs), triggering muscle development.

    Limbs Development

    • Limb Bud Formation: Limb buds emerge from lateral body wall during the fourth week, initially consisting of mesenchymal core covered by ectoderm.

    • AER (Apical Ectodermal Ridge): Ectodermal ridge at limb tip promotes undifferentiated growth of mesenchymal cells; differentiation occurs further away.

    • Limb Development Pathway: First, humerus/femur, followed by radius/ulna/tibia/fibula, then carpals/tarsals, metacarpals/metatarsals, and digits.

    • Limb Rotation: Upper limbs rotate laterally, lower limbs medially.

    • Hand/Foot Formation: Hand and foot plates form at 6 weeks, separated by constrictions.

    • Finger/Toe Formation: Cell death in the AER leads to digit separation; outgrowth and condensation of mesenchyme are crucial for formation of digits.

    Limb Defects

    • Amelia: Complete limb absence.
    • Meromelia: Partial limb absence.
    • Micromelia: Shortened limbs.
    • Brachydactyly: Shortened digits.
    • Syndactyly: Fused digits.
    • Polydactyly: Extra digits.

    Other Concepts

    • Somitomeres vs. Somites: Somitomeres are early, precursors to somites in the head/trunk; somites are segmented blocks in trunk/tail regions.

    • Lateral Somitic Frontier: Border between somites and lateral plate mesoderm, creating primaxial/abaxial domains.

    • Tendons: Derived from sclerotome cells adjacent to myotomes; regulated by scleraxis.

    • Joints Formation: Cartilage-condensation arrest leads to joint formation with cell death creating a joint cavity.

    • Clinical Correlates: Bone age assessed prenatally or postnatally by ossification centres; defects are visible as abnormal development, lack of formation, fusion.

    • Nerve Supply: Spinal nerves innervate specific muscle groups.

    • Muscular System Defects: Various muscle absence issues or malformations, which are not usually critical. Specific cases are discussed individually. eg, Poland Anomaly, Prune Belly Syndrome. Potential life-threatening issues are noted.

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    Description

    Test your knowledge on embryonic tissues and the skeletal development process. This quiz covers questions related to the formation of bones, structures derived from mesoderm, and various limb defects. Perfect for students studying embryology or anatomy.

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