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Questions and Answers
What is the collective term for the structures formed by the cells in the A region of somite differentiation?
What is the collective term for the structures formed by the cells in the A region of somite differentiation?
Which process is primarily responsible for the epithelialization of somites?
Which process is primarily responsible for the epithelialization of somites?
What signal is known to inhibit somitogenesis?
What signal is known to inhibit somitogenesis?
Which statement best describes the size of somites during early development?
Which statement best describes the size of somites during early development?
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What is the collective term for the structures derived from the B region of somite differentiation?
What is the collective term for the structures derived from the B region of somite differentiation?
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Which transcription factor is associated with the epithelialization of somites?
Which transcription factor is associated with the epithelialization of somites?
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Which structure would cells in the E region of somite differentiation contribute to?
Which structure would cells in the E region of somite differentiation contribute to?
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What is the outcome when N-cadherin is lost during somite development?
What is the outcome when N-cadherin is lost during somite development?
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What is the role of Pax 1 and Scleraxis in endochondral bone formation?
What is the role of Pax 1 and Scleraxis in endochondral bone formation?
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During which phase do mesenchyme cells condense into compact nodules and begin to differentiate into chondrocytes?
During which phase do mesenchyme cells condense into compact nodules and begin to differentiate into chondrocytes?
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What is the significance of N-cadherin in the process of endochondral bone formation?
What is the significance of N-cadherin in the process of endochondral bone formation?
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What occurs during the fifth phase of endochondral bone formation?
What occurs during the fifth phase of endochondral bone formation?
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Which factor acts as a master regulator of early chondrogenesis?
Which factor acts as a master regulator of early chondrogenesis?
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What role does PTHrP play in the zone of hypertrophic chondrocytes?
What role does PTHrP play in the zone of hypertrophic chondrocytes?
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Which protein is crucial for maintaining chondrocyte condensations?
Which protein is crucial for maintaining chondrocyte condensations?
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What effect does FGFr3 have on chondrocyte behavior?
What effect does FGFr3 have on chondrocyte behavior?
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What is the role of PDGF in the context of vertebrae formation?
What is the role of PDGF in the context of vertebrae formation?
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Which structures originate from the sclerotome?
Which structures originate from the sclerotome?
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What are Hox genes primarily responsible for in vertebral column development?
What are Hox genes primarily responsible for in vertebral column development?
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What initiates endochondral bone formation?
What initiates endochondral bone formation?
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Which statement accurately describes N-cadherin in bone formation?
Which statement accurately describes N-cadherin in bone formation?
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What does the process of endochondral ossification involve?
What does the process of endochondral ossification involve?
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What factor induces endothelial cell differentiation in blood vessels?
What factor induces endothelial cell differentiation in blood vessels?
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Which developmental aspect is primarily associated with the dermomyotome?
Which developmental aspect is primarily associated with the dermomyotome?
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Which transcription factor is essential for specifying the osteoblast lineage?
Which transcription factor is essential for specifying the osteoblast lineage?
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What occurs in the absence of sex hormones like estrogen in menopausal women?
What occurs in the absence of sex hormones like estrogen in menopausal women?
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Which growth factors are responsible for inducing neural crest cells to express cbfa genes?
Which growth factors are responsible for inducing neural crest cells to express cbfa genes?
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Which of the following is NOT a hallmark of hypertrophic chondrocytes?
Which of the following is NOT a hallmark of hypertrophic chondrocytes?
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What type of ossification is involved in the development of dermal bones like the skull?
What type of ossification is involved in the development of dermal bones like the skull?
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How do osteoprogenitor cells contribute to bone development?
How do osteoprogenitor cells contribute to bone development?
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What is the main function of Osx in chondrocytes and osteoblasts?
What is the main function of Osx in chondrocytes and osteoblasts?
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What triggers the closure of the growth plate during puberty?
What triggers the closure of the growth plate during puberty?
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What is the primary role of Bmp in suture maintenance during growth?
What is the primary role of Bmp in suture maintenance during growth?
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Which structure is responsible for differentiating into muscle precursors and brown fat cells?
Which structure is responsible for differentiating into muscle precursors and brown fat cells?
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Which factors primarily stimulate proliferation and differentiation in muscle development?
Which factors primarily stimulate proliferation and differentiation in muscle development?
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What function does neuregulin-1 serve in myogenic progenitor maintenance?
What function does neuregulin-1 serve in myogenic progenitor maintenance?
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What term describes the division of mesoderm into sclerotome and dermomyotome?
What term describes the division of mesoderm into sclerotome and dermomyotome?
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Which of the following is a reason why myostatin is significant in muscle development?
Which of the following is a reason why myostatin is significant in muscle development?
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Which signaling pathways are involved in the differentiation into myotome?
Which signaling pathways are involved in the differentiation into myotome?
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What is the role of FGF signals in dermomyotome development?
What is the role of FGF signals in dermomyotome development?
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What is a characteristic of muscle masses during development?
What is a characteristic of muscle masses during development?
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Which type of muscles is associated with the abaxial muscles of the dermomyotome?
Which type of muscles is associated with the abaxial muscles of the dermomyotome?
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Study Notes
Mesodermal Structures
- The title of the document/lecture is Mesodermal Structures, authored by Lerrie Ann Ipulan-Colet, Gilbert and Barresi, 11th Edition.
Somitogenesis: Directionality and Size
- Questions about somitogenesis:
- Is there directionality in somite creation?
- Are somites of the same size?
- Which somite is older, SIV or SI?
Boundary Formation
- Questions pertaining to boundary formation:
- What events are needed for A/P elongation of somites?
- Which signals inhibit and induce somitogenesis?
- Which signal is responsible for somite epithelialization?
- What morphogenetic/cellular event is necessary for epithelium formation?
Analogies in Somitogenesis
- Analogies in somitogenesis:
- Morphological analogies- pan deasal/bread making, candy, chorizo/longanisa, plant nodes/internodes
- Molecular analogies- toxic jowa, sunscreen/sunburn.
Partitions and Lineages of the Mesoderm
- Parts and lineages:
- Neural tube
- Intermediate mesoderm
- Chordamesoderm
- Paraxial mesoderm
- Lateral plate mesoderm
- Notochord
- Somite
- Kidney
- Gonads
- Head
- Intervertebral disc
- Sclerotome
- Myotome
- Dermatome
- Syndetome
Somitogenesis: Formation
- Points of discussion:
- Epithelialization- expression of fibronectin, cadherins. May be due to transcription factor (Paraxis)
- Specification- axial specification happens early (e.g., only certain somites form ribs).
- Epithelial Mesenchymal Transition (EMT)
- Differentiation within somites
- Watch Barressi video
Somitogenesis: Determination
- Elements in somitogenesis determination:
- BMP4
- NT3, Wntl, Pax3, 7
- Wnt
- Wnt3a
- Myf5, Pax3
- MyoD
- Pax1
- BMP4, FGF5
- Shh
- Noggin
- Epidermis
- Dermatome
- Abaxial (body wall and limb) muscles
- Lateral plate mesoderm
- Sclerotome
- Dermomyotome
- Neural tube
- Floor plate
- Notochord
- Shh
EMT in the Somite
- Elements in EMT in somite:
- Embryo diagrams (2 days, 3 days, 4 days and late 4 days)
- Epidermis
- Neural tube
- Sclerotome progenitors
- Floorplate
- Notochord
- Dermomyotome
- Primaxial dermomyotome lip
- Primaxial myotome
- Sclerotome
- Dermatome region
- Paxl – migrating sclerotome
- Abaxial myotome
- Abaxial dermomyotome lip
- Central myotome region
Epimere/Somites
- Epimere/somite divisions:
- Sclerotome development
- Vertebrae development
- Bone development
- Dermomyotome development
- Myotome
- Dermatome
- Migrating myoblast
- Sclerotome development
Somite Differentiation
- Questions about Somite Differentiation:
- What is the collective term for A?
- What is the collective term for B?
- What structures do D contribute?
- What do cells in C contribute to?
- What do cells in E contribute to?
Endochondral Bone Formation
- Information about Endochondral Bone Formation:
- Involves blood vessel invasion of the cartilage model
- Hypertrophic chondrocytes die via apoptosis
- Osteoblasts deposit bone matrix in periphery
- Mesenchyme (in sclerotome, limbs)
- Induced to secrete Pax I and Scleraxis
- Activates cartilage-specific genes
- Chondrocytes proliferate rapidly to form the model
- Chondrocytes secrete cartilage-specific ECM
- Committed mesenchyme cells
- Compact nodules
- Chondrocytes
- N-cadherin
- N-CAM
- Cells become hypertrophic chondrocytes
- Matrix alters by adding collagen X and fibronectin
- Mineralized calcium are easily deposited
- Cartilage
- Hypertrophic chondrocytes
- Osteoblasts
- Blood vessels
Endochondral Bone Development
- Points about Endochondral Bone Development:
- Sox Trio - master regulator of early chondrogenesis
- Commitment of mesenchymal cells to cartilage (Sox 9)
- Secretion of critical collagen (Sox 9)
- Sox5 and 6 deficient mice have chondroplasia
- BMP
- Mesenchymal condensation
- Pro-proliferation and anti-differentiation
- FGFr3
- Accelerate chondrocyte proliferation and differentiation
- Constitutive active mutations lead to skeletal dysplasia (ex, short limbs and dwarfism)
- PTHrP
- Gatekeeper of zone of hypertrophic chondrocytes
- Control switch from proliferative immature chondrocyte to post-proliferative hypertrophic chondrocyte
- Sox Trio - master regulator of early chondrogenesis
Runx's New Role
- Runx's New Role
- Runx2 essential for specifying osteoblast lineage
- Directly regulates another transcription factor (Osterix)
- Regulates Coll0al and matrix metalloproteinase-13 (Mmp13) expression in chondrocytes
- Osx essential for preosteoblast differentiation
- Osx transactivates Collal
- Encodes collagen I, a marker of differentiated osteoblasts
- Hypertrophic chondrocytes can become osteoblasts and osteocytes
Growth Plate and Hormonal Influence
- Growth Plate and Hormonal Influence:
- Influenced by growth hormone and IGF
- Puberty growth spurt due to sex hormones
- Growth plate closure eventually
- Absence of sex hormone (estrogen)
- Leads to osteoporosis in menopausal women
Development of Dermal Bones
- Dermal Bone Development:
- Derived from intramembranous ossification
- Skull, jaws, gill covers, fin spines, rays, and shell in humans
- Human skull from both neural crest cells (NCC) and mesoderm
- BMP2, 4, and 7 induce neural crest cells
- Expression of cbfa genes
- Leads to expression of bone-specific ECM proteins
Development of the Skull
- Development of the Skull:
- FEZ regulates growth and frontonasal patterning
- D-V patterning (Chick model)
- FEZ/frontonasal ectodermal zone
- Midfacial ectoderm coordinates frontonasal and plate development
- Fgf8 and Shh boundary
- Osteo progenitors migrate and add to leading edges of developing bones
- Signaling impacts suture maintenance for further growth
- Bmp - bone formation
- Jag1 - osteogenic font
- Twist – mifration
What is Craniosynostosis?
- Craniosynostosis:
- Sagittal suture (affected suture) is fused prematurely
Other Structures from Sclerotome
- Other Structures from Sclerotome:
- Tendons- scleraxis-expressing part of the scleretome
- Dorsal aorta- posterior sclerotome origin of ECs and vSMCs
- Other arteries- lateral plate mesoderm
- EC differentiation induced by Notch sign in Ephrin B2-dependent manner
Myogenesis of Skeletal Muscle Fiber
- Myogenesis of Skeletal Muscle Fiber:
- Formation of non-specific muscle masses
- Break up into discrete units (primordia) of individual muscles
- Differentiation of myotubes from myoblasts
- Innervation
- Motor innervation
- Sensory innervation
- Formation of non-specific muscle masses
Factors Regulating Muscle Development
- Factors regulating muscle development:
- Insulin-like growth factor-1 and -2
- Stimulates proliferation
- Stimulates differentiation
- Fibroblast Growth Factor
- Stimulates proliferation
- Inhibits differentiation
- Transforming growth factor beta
- Suppresses proliferation
- Suppresses differentiation
- Myostatin
- Negative regulator
- Insulin-like growth factor-1 and -2
Model of Muscle Cell Development
- Model of Muscle Cell Development:
- Specification and formation of myoblast
- Myoblasts --> proliferation
- Myogenin (active) --> differentiation
- Myotubes
- p21
- p57
- Cyclin Dependent Kinases
- Growth Factors (ex, IGF1)
Categorizing Factors That Affect Myogenesis
- Categorizing Factors:
- Column A (pro-myogenesis)
- Pro-proliferation
- Pro-differentiation
- Pro-increase in muscle size
- Column B (anti-myogenesis)
- Anti-proliferation
- Anti-differentiation
- Anti-increase in muscle size
- Column A (pro-myogenesis)
Defect in Bone/Muscle Formation
- Defect Information:
- Mechanisms of defects (2-3 sentences)
- Biological effect (2-3 sentences)
- How to ameliorate the defect (2-3 sentences)
- Reference list
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Description
Test your knowledge on mesodermal structures, including somitogenesis, boundary formation, and morphological analogies. This quiz covers key concepts such as directionality in somite creation and the events necessary for epithelialization. Dive into the intricate details of the mesoderm and challenge your understanding!
