Talk:2010 BGD Practical 6 - Week 3: Difference between revisions
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* [[Neurogenesis]] | * [[Neurogenesis]] | ||
==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 '''[[S#somite|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. | |||
<gallery> | |||
File:Stage10 bf4b.jpg|Early stage 10 | |||
File:Stage10 bf5b.jpg|Late stage 10 | |||
File:Stage10 bf6b.jpg|Labeled stage 10 | |||
</gallery> | |||
<gallery> | |||
Image:Mesoderm cartoon1.gif|trilaminar embryo | |||
Image:Mesoderm cartoon2.gif|mesoderm regions | |||
Image:Mesoderm cartoon3.gif|somite coelom | |||
Image:Mesoderm cartoon4.gif|neural tube and neural crest | |||
</gallery> | |||
'''Mesoderm organization:''' lateral plate - intermediate mesoderm - paraxial mesoderm - axial mesoderm - paraxial mesoderm - intermediate mesoderm - lateral plate | |||
<gallery> | |||
Image:Stage7_paraxial-mesoderm.jpg|Stage 7 paraxial mesoderm | |||
Image:Stage7_intermediate-mesoderm.jpg|Stage 7 intermediate mesoderm | |||
Image:Stage7_lateral-plate.jpg|Stage 7 lateral plate | |||
</gallery> | |||
===Axial Mesoderm=== | |||
* notochord | |||
# mechanical role in embryonic disc folding | |||
# molecular role in patterning surrounding tissues | |||
<gallery> | |||
Image:Stage7_800x700px.jpg|Stage 7 embryonic disc | |||
Image:Stage7_primitive-streak-node.jpg|Stage 7 primitive-streak-node | |||
Image:Stage7_cloacal-oral-membranes.jpg|Stage 7 cloacal-oral-membranes | |||
Image:Stage7 notochord.jpg|Stage 7 notochord | |||
</gallery> | |||
'''Adult''' - contributes to the nucleus pulposis of the intervertebral disc | |||
===Paraxial Mesoderm=== | |||
[[Image:Stage7_paraxial-mesoderm.jpg|thumb|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=== | |||
[[Image:Stage7_intermediate-mesoderm.jpg|thumb|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 | |||
# pronephros | |||
# mesonephros | |||
# metanephros | |||
'''Adult''' - metanephros forms the kidney | |||
===Lateral Plate Mesoderm=== | |||
[[Image:Stage7_lateral-plate.jpg|thumb|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=== | |||
[[File:Stage11 sem100c.jpg|stage 11 Embryo]] | |||
Somite initially forms 2 main components | |||
* ventromedial- sclerotome forms vertebral body and intervertebral disc | |||
* dorsolateral - dermomyotome forms dermis and skeletal muscle | |||
<gallery> | |||
Image:Somite cartoon1.png|paraxial mesoderm | |||
Image:Somite cartoon2.png|early somite | |||
Image:Somite cartoon3.png|sclerotome and dermomyotome | |||
Image:Somite cartoon4.png|dermatome and myotome | |||
Image:Somite cartoon5.png|epaxial and hypaxial muscles | |||
</gallery> | |||
===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 | |||
[[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 10:53, 16 May 2010
Week 3
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
- mechanical role in embryonic disc folding
- molecular role in patterning surrounding tissues
Adult - contributes to the nucleus pulposis of the intervertebral disc
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
- named by position (between paraxial and lateral plate)
- differentiates rostro-caudally (head to tail)
- forms 3 sets of "kidneys" in sequence
- pronephros
- mesonephros
- metanephros
Adult - metanephros forms the kidney
Lateral Plate Mesoderm
- 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
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