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Questions and Answers
What role does Bone morphogenetic protein 4 (BMP4) play in muscle development?
What role does Bone morphogenetic protein 4 (BMP4) play in muscle development?
- It is involved in the formation of muscle vascularization.
- It signals dermomyotome cells to produce MyoD. (correct)
- It directly stimulates muscle contraction.
- It provides nutritional support for muscle cells.
Which proteins are secreted by the notochord and floor plate of the neural tube during muscle development?
Which proteins are secreted by the notochord and floor plate of the neural tube during muscle development?
- WNT proteins
- Sonic hedgehog (SHH) proteins (correct)
- Fibroblast growth factors
- BMP4 proteins
Which cells are indicated to be influenced by WNT proteins from the dorsal neural tube?
Which cells are indicated to be influenced by WNT proteins from the dorsal neural tube?
- Abaxial muscle cells
- Ventral dermomyotome cells
- VLL cells of the dermomyotome (correct)
- Primaxial muscle cells
In the context of muscle development, what distinguishes primaxial domains from abaxial domains?
In the context of muscle development, what distinguishes primaxial domains from abaxial domains?
What is the difference between epimeres and hypomeres in muscle classification?
What is the difference between epimeres and hypomeres in muscle classification?
What is a characteristic feature of Poland sequence?
What is a characteristic feature of Poland sequence?
Poland sequence is primarily attributed to which type of tissue development?
Poland sequence is primarily attributed to which type of tissue development?
What unusual digital defects may occur in individuals with Poland sequence?
What unusual digital defects may occur in individuals with Poland sequence?
Cardiac muscle myofibrils share similarities with which type of muscle?
Cardiac muscle myofibrils share similarities with which type of muscle?
What component facilitates the adherence of myoblasts in developing cardiac muscle?
What component facilitates the adherence of myoblasts in developing cardiac muscle?
Which of the following statements about Poland sequence is FALSE?
Which of the following statements about Poland sequence is FALSE?
The muscles in the head and neck during the embryonic stage are derived from which source?
The muscles in the head and neck during the embryonic stage are derived from which source?
What is the result of cardiac muscle development from splanchnic mesoderm?
What is the result of cardiac muscle development from splanchnic mesoderm?
Which type of muscle is derived from the splanchnic layer of lateral plate mesoderm?
Which type of muscle is derived from the splanchnic layer of lateral plate mesoderm?
Which transcription factor is primarily responsible for smooth muscle differentiation?
Which transcription factor is primarily responsible for smooth muscle differentiation?
What role do Myocardin and MRTFs play in smooth muscle development?
What role do Myocardin and MRTFs play in smooth muscle development?
From where does the mesenchyme that contributes to limb musculature originate?
From where does the mesenchyme that contributes to limb musculature originate?
When is the first indication of limb musculature observed during development?
When is the first indication of limb musculature observed during development?
What initiates the genetic cascade responsible for smooth muscle development?
What initiates the genetic cascade responsible for smooth muscle development?
What is NOT a derived structure from the ectoderm?
What is NOT a derived structure from the ectoderm?
Which somite group contributes to the development of the craniofacial muscles?
Which somite group contributes to the development of the craniofacial muscles?
What comprises the abaxial muscle cell precursors?
What comprises the abaxial muscle cell precursors?
Which cells are primarily responsible for forming tendons during muscle development?
Which cells are primarily responsible for forming tendons during muscle development?
Which region do the VLL cells migrate to in muscle development?
Which region do the VLL cells migrate to in muscle development?
What is formed from cells at the DML and VLL regions of the somite?
What is formed from cells at the DML and VLL regions of the somite?
What differentiates the primaxial mesodermal domain from the abaxial mesodermal domain?
What differentiates the primaxial mesodermal domain from the abaxial mesodermal domain?
From where do primaxial muscle cell precursors primarily receive their developmental signals?
From where do primaxial muscle cell precursors primarily receive their developmental signals?
What do somite-derived cells contribute to in the context of muscle cell formation?
What do somite-derived cells contribute to in the context of muscle cell formation?
What is the primary origin of muscle cell precursors in the ventral region ventral to the dermatome?
What is the primary origin of muscle cell precursors in the ventral region ventral to the dermatome?
What is a characteristic feature of Prune Belly Syndrome?
What is a characteristic feature of Prune Belly Syndrome?
Which embryonic origin is responsible for smooth muscle in coronary arteries?
Which embryonic origin is responsible for smooth muscle in coronary arteries?
Which signal induces VIL in the development of smooth muscle?
Which signal induces VIL in the development of smooth muscle?
What type of musculature is affected in Prune Belly Syndrome?
What type of musculature is affected in Prune Belly Syndrome?
What causes the accumulation of fluid in the abdomen associated with Prune Belly Syndrome?
What causes the accumulation of fluid in the abdomen associated with Prune Belly Syndrome?
What does the connective tissue generate in muscle pattern establishment?
What does the connective tissue generate in muscle pattern establishment?
Which signals from the notochord induce DML cells?
Which signals from the notochord induce DML cells?
From which embryonic layer are the smooth muscles of the dorsal aorta and large arteries derived?
From which embryonic layer are the smooth muscles of the dorsal aorta and large arteries derived?
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Study Notes
Myofibril Formation and Muscle Development
- Distributed myofibrils emerge during later stages of muscular development.
- Cardiac conduction fibers originate from specialized muscle cells crucial for heart function.
- Smooth muscle in large arteries and the dorsal aorta develops from lateral plate mesoderm and neural crest cells.
Prune Belly Syndrome
- Characterized by partial or complete absence of abdominal muscles, leading to visible and palpable organs.
- Common malformations include urinary tract defects and bladder issues, such as urethral obstruction.
- This condition can result in fluid accumulation in the abdomen, causing muscle atrophy.
Poland Sequence
- Occurs in approximately 1 in 20,000 individuals.
- Noted for the absence of the pectoralis minor muscle and partial loss of the pectoralis major, specifically the sternal head.
- Accompanying symptoms may include nipple and areola displacement and digital defects such as syndactyly and brachydactyly.
Cardiac Muscle Development
- Cardiac muscle arises from splanchnic mesoderm around the endothelial heart tube.
- Myoblasts form intercalated discs through cell adhesion, essential for cardiac function.
- Purkinje fibers, unique muscle cell bundles, develop from remaining embryonic muscle cells.
Dermomyotome and Muscle Patterning
- Dermomyotome is derived from the combination of ventrolateral (VLL) and dorsomedial (DML) cells.
- Abaxial muscle cell precursors migrate into lateral plate mesoderm, influenced by signals from the neural tube and notochord.
- Primaxial muscle cells remain in the paraxial mesoderm, relying on locally sourced developmental signals.
Molecular Regulation of Muscle Development
- Bone morphogenetic protein 4 (BMP4) and fibroblast growth factors guide differentiation in muscle cells.
- WNT proteins stimulate VLL cells to express muscle-specific gene MyoD, vital for muscle development.
- Sonic hedgehog (SHH) signaling from the notochord also impacts the DML cells for muscle patterning.
Innervation of Axial Skeletal Muscles
- Each myotome is innervated by spinal nerves from the same segment, ensuring coordinated function.
- New classification of muscle development splits muscles into primaxial (back) and abaxial (limb) domains, replacing older definitions based on innervation styles.
Smooth Muscle Sources
- Smooth muscle in the gut wall and related organs arises from the splanchnic layer of lateral plate mesoderm.
- Sphincter muscles, pupil muscles, and glandular tissues come from ectoderm.
- Serum Response Factor (SRF) is crucial for smooth muscle differentiation, influenced by growth factors and signaling pathways.
Limb Musculature
- Initial limb musculature appears in week 7 of embryonic development as mesenchymal condensation.
- This mesenchyme originates from dorsolateral somite cells that migrate to limb buds to establish the muscular framework.
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