Difference between revisions of "Talk:2010 BGD Practical 6 - Week 3"

From Embryology
(Created page with '== Week 3 == thumb|Week 3 - Embryonic disc * Week 3 - Carnegie stage 7 | 8 | 9 *…')
 
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* [[Neurogenesis]]
 
* [[Neurogenesis]]
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==Week 3==
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'''Mesoderm''' means the "middle layer" and it is from this layer that nearly all the bodies connective tissues are derived. In early mesoderm development a number of transient structures will form and then be lost as  tissue structure is patterned and organised. Humans are vertebrates, with a "backbone", and the first  mesoderm structure we will see form after the notochord will be '''[[S#somite|somites]]'''.
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Facts: Week 4, 22 - 23 days, 2 - 3.5 mm, Somite Number 4 - 12
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View: This is a dorsal view of the human embryo, the amniotic membrane has been removed. Top embryo is an early stage 10, bottom is late stage 10.
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<gallery>
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File:Stage10 bf4b.jpg|Early stage 10
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File:Stage10 bf5b.jpg|Late stage 10
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File:Stage10 bf6b.jpg|Labeled stage 10
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</gallery>
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<gallery>
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Image:Mesoderm cartoon1.gif|trilaminar embryo
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Image:Mesoderm cartoon2.gif|mesoderm regions
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Image:Mesoderm cartoon3.gif|somite coelom
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Image:Mesoderm cartoon4.gif|neural tube and neural crest
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</gallery>
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'''Mesoderm organization:''' lateral plate - intermediate mesoderm - paraxial mesoderm - axial mesoderm - paraxial mesoderm - intermediate mesoderm - lateral plate
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<gallery>
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Image:Stage7_paraxial-mesoderm.jpg|Stage 7 paraxial mesoderm
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Image:Stage7_intermediate-mesoderm.jpg|Stage 7 intermediate mesoderm
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Image:Stage7_lateral-plate.jpg|Stage 7 lateral plate
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</gallery>
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===Axial Mesoderm===
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* notochord
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# mechanical role in embryonic disc folding
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# molecular role in patterning surrounding tissues
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<gallery>
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Image:Stage7_800x700px.jpg|Stage 7 embryonic disc
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Image:Stage7_primitive-streak-node.jpg|Stage 7 primitive-streak-node
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Image:Stage7_cloacal-oral-membranes.jpg|Stage 7 cloacal-oral-membranes
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Image:Stage7 notochord.jpg|Stage 7 notochord
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</gallery>
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'''Adult''' - contributes to the nucleus pulposis of the intervertebral disc
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===Paraxial Mesoderm===
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[[Image:Stage7_paraxial-mesoderm.jpg|thumb|Stage 7 paraxial mesoderm]]
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* differentiates rostro-caudally (head to tail)
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* remains unsegmented in the head region.
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* segments in the body region to form pairs of somites along the length of the embryo.
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'''Adult''' - contributes vertebral column (vertebra and IVD), dermis of the skin, skeletal muscle of body and limbs
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===Intermediate Mesoderm===
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[[Image:Stage7_intermediate-mesoderm.jpg|thumb|Stage 7 intermediate mesoderm]]
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* named by position (between paraxial and lateral plate)
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* differentiates rostro-caudally  (head to tail)
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* forms 3 sets of "kidneys" in sequence
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# pronephros
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# mesonephros
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# metanephros
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'''Adult''' - metanephros forms the kidney
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===Lateral Plate Mesoderm===
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[[Image:Stage7_lateral-plate.jpg|thumb|Stage 7 lateral plate]]
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* a "horseshoe shaped" space forms in the middle
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* somatic mesoderm - closest to ectoderm
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* space - forms the 3 body cavities (pericardial, pleural, peritoneal)
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* splanchnic mesoderm - closest to endoderm
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'''Adult''' - body connective tissues, gastrointestinal tract (connective tissues, muscle, organs), heart
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===Somite Development===
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[[File:Stage11 sem100c.jpg|stage 11 Embryo]]
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Somite initially forms 2 main components
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* ventromedial- sclerotome forms vertebral body and intervertebral disc
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* dorsolateral - dermomyotome forms dermis and skeletal muscle
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<gallery>
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Image:Somite cartoon1.png|paraxial mesoderm
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Image:Somite cartoon2.png|early somite
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Image:Somite cartoon3.png|sclerotome and dermomyotome
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Image:Somite cartoon4.png|dermatome and myotome
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Image:Somite cartoon5.png|epaxial and hypaxial muscles
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</gallery>
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===Sclerotome===
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* sclerotome later becomes subdivided
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** rostral and caudal halves separated laterally by von Ebner's fissure
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* half somites contribute to a single vertebral level body
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* other half intervertebral disc
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* therefore final vertebral segmentation “shifts”
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===Myotome===
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* Body - epaxial and hypaxial muscles
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* Limbs - flexor and extensor muscles
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===Dermatome===
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* connective tissue underlying epidermis
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* begins as a dorsal thickening
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* spreads throughout the body
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[[File:Mesoderm 001 icon.jpg|160px|link=Development_Animation_-_Mesoderm]] [[File:Somite 001 icon.jpg|160px|link=Development_Animation_-_Somite_Musculoskeletal]]  [[File:Vertabra 003 icon.jpg|160px|link=Development_Animation_-_Vertebra]]

Revision as of 11:53, 16 May 2010

Week 3

Week 3 - Embryonic disc

Week 3

Mesoderm means the "middle layer" and it is from this layer that nearly all the bodies connective tissues are derived. In early mesoderm development a number of transient structures will form and then be lost as tissue structure is patterned and organised. Humans are vertebrates, with a "backbone", and the first mesoderm structure we will see form after the notochord will be somites.

Facts: Week 4, 22 - 23 days, 2 - 3.5 mm, Somite Number 4 - 12

View: This is a dorsal view of the human embryo, the amniotic membrane has been removed. Top embryo is an early stage 10, bottom is late stage 10.

Mesoderm organization: lateral plate - intermediate mesoderm - paraxial mesoderm - axial mesoderm - paraxial mesoderm - intermediate mesoderm - lateral plate

Axial Mesoderm

  • notochord
  1. mechanical role in embryonic disc folding
  2. molecular role in patterning surrounding tissues

Adult - contributes to the nucleus pulposis of the intervertebral disc

Paraxial Mesoderm

Stage 7 paraxial mesoderm
  • differentiates rostro-caudally (head to tail)
  • remains unsegmented in the head region.
  • segments in the body region to form pairs of somites along the length of the embryo.

Adult - contributes vertebral column (vertebra and IVD), dermis of the skin, skeletal muscle of body and limbs

Intermediate Mesoderm

Stage 7 intermediate mesoderm
  • named by position (between paraxial and lateral plate)
  • differentiates rostro-caudally (head to tail)
  • forms 3 sets of "kidneys" in sequence
  1. pronephros
  2. mesonephros
  3. metanephros

Adult - metanephros forms the kidney

Lateral Plate Mesoderm

Stage 7 lateral plate
  • a "horseshoe shaped" space forms in the middle
  • somatic mesoderm - closest to ectoderm
  • space - forms the 3 body cavities (pericardial, pleural, peritoneal)
  • splanchnic mesoderm - closest to endoderm

Adult - body connective tissues, gastrointestinal tract (connective tissues, muscle, organs), heart

Somite Development

stage 11 Embryo

Somite initially forms 2 main components

  • ventromedial- sclerotome forms vertebral body and intervertebral disc
  • dorsolateral - dermomyotome forms dermis and skeletal muscle

Sclerotome

  • sclerotome later becomes subdivided
    • rostral and caudal halves separated laterally by von Ebner's fissure
  • half somites contribute to a single vertebral level body
  • other half intervertebral disc
  • therefore final vertebral segmentation “shifts”

Myotome

  • Body - epaxial and hypaxial muscles
  • Limbs - flexor and extensor muscles

Dermatome

  • connective tissue underlying epidermis
  • begins as a dorsal thickening
  • spreads throughout the body

Mesoderm 001 icon.jpg Somite 001 icon.jpg Vertabra 003 icon.jpg