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Early Development of the Ectoderm
DrAnnemiekBeverdam– SchoolofMedicalSciences,UNSWWallaceWurth BuildingRoom234– A.Beverdam@unsw.edu.au
Resources:http://php.med.unsw.edu.au/embryology/
Larsen’s Human EmbryologyThe Developing Human: Clinically Oriented Embryology
Lecture overviewEarly Development of the Ectoderm
Gastrulation and Embryonic Folding
Neurulation
Early Development of the Nervous System
Neural Crest
Epidermis Development
Ectodermal placodes
Neural Tube Defects
DrAnnemiekBeverdam– SchoolofMedicalSciences,UNSWWallaceWurth BuildingRoom234– A.Beverdam@unsw.edu.au
Resources:http://php.med.unsw.edu.au/embryology/
Larsen’s Human EmbryologyThe Developing Human: Clinically Oriented Embryology
Week 3: gastrulation:Primitive streak and node
Ingression of epiblast cells: EMT transitionGeneration of endodermGeneration of mesodermGeneration of ectoderm
Oropharyngeal and cloacal membrane
Week 3: Gastrulation
Epiblast forms 3 germ layers:- Ectoderm: epithelium (previous epiblast)- Mesoderm: mesenchymal layer (embryonic connective tissue)- Endoderm: epithelium
Hypoblast:- replaced by definitive endoderm
3 body axes:- Anteroposterior or cranial to caudal body axis- Dorsoventral body axis- Left-Right body axis
3 weeks
37 weeks
Embryonic development:
End product gastrulation:Trilaminar embryo
Ectoderm (Neural crest)brain, spinal cord, eyes, peripheral nervous system
epidermis of skin and associated structures, melanocytes, cranial connective tissues (dermis)
Mesodermmusculo-skeletal system, limbs,
connective tissue of skin and organs,urogenital system, heart, blood cells
Endodermepithelial linings of gastrointestinal, liver, pancreas,
thyroid and respiratory tracts
Embryo foldingGeneration of primitive gut
Neural plate and neural tube
http://php.med.unsw.edu.au/embryology/images/2/27/Week3_folding.mp4
Page342S.F.GilbertDevelopmentalBiology5thedition
Early ectoderm development:
EctodermMidplate ectoderm:nervoussystemandneuralcrest
Lateralectoderm:surfaceepidermisEctodermalplacodes
Midplate Ectoderm
NeuralinductionbytheprimitivenodeNeuralplate=neuroepithelium
NeuralplategivesrisetotheCNSandtheneuralcrestNeuralgroove
NeurulationMidplate ectoderm4mainevents:-1neuralplateformation-2shapingoftheneuralplate-3bendingoftheneuralplate-4closureoftheneuralgroove
NeurulationMidplate ectoderm
TheneuraltubezipsupfromcentertowardsbothendsCranialandcaudalneuropores
Closureofcaudalneuropore completesneurulation
NeurulationMidplate ectoderm
EctodermMidplate ectoderm:nervoussystemandneuralcrest
Lateralectoderm:surfaceepidermisEctodermalplacodes
Neurulation
Neurulation
Neurulation
NeurulationSecondary neurulation
Closure of caudal neuropore completes neurulationSecondary neurulation occurs posteriorly of nodeCondensation of tail bud cells into medullary cord
CavitationLumen merges with neural canal
Neurulation
Early development of the CNS
Cephalicflexure
Cervicalflexure
3primarybrainvesicles2flexures
Early development of the CNS5secondarybrainvesicles
3flexures
Cephalicflexure
Cervicalflexure
Pontineflexure
Early development of the CNS
5-weekembryo
Early development of the CNS
Neurulation
Early development of the CNS
Brain VentriclesAmniotic fluid -> Cerebrospinal Fluid
Continuous with central canal of neural tubeCSF is produced by choroid plexus
Hydrocephalus
Spinal Cord AxesDorsoventral axis
Dorsalhorns:interneuronsreceivingsensoryinputVentralhorns:motorneurons
Spinal Cord AxesDorsoventral axis
Spinal Cord AxesAnteroposterior axis
AdaptedfromLewisWolpert etal.,1998
Spinal Cord AxesAnteroposterior axis
Spinal Cord AxesAnteroposterior axis
Hostikka etal.,2009
Cytodifferentation of the Neural TubeTime
Neural Crest Development
Neural Crest Development
Neural Crest Development4 functional domains and lineages
Cranialneuralcrest:Cranialmesenchyme,facialskeleton,cranialnerveganglia
Cardiacneuralcrest:Melanocytes,cartilage,connectivetissueandneuronsofsomepharyngealarches,Contributestoformationofregionsoftheheart
Trunkneuralcrest:Melanocytes,dorsalrootganglia,sympatheticganglia,adrenalmedulla,nervessurroundingaorta
VagalandSacralneuralcrest:Melanocytes,gangliaoftheentericnervoussystemParasympatheticganglia
Neural Crest Development
Neural Crest Development
Epidermal developmentLateral surface ectoderm
Interfollicular epidermis(surfaceepithelium)
EpidermalAppendages:HairfolliclesGlands(sebaceous,sweat,apocrine)MammaryglandsNailsTeeth
Ectodermal placodesOtic placodesOlfactory(Nasal)placodesOptic(Lens)placodesAdenohypophyseal placodeProfundal/trigeminalplacodes
SpecializedectodermalthickeningsincranialregionContributetosensorystructures,teethandpituitary
Ectodermal placodes
Otic placodesOlfactory(Nasal)placodesOptic(Lens)placodesAdenohypophyseal placodeProfundal/trigeminalplacodes
Neural Tube Defects
Dysraphism:Spinabifidaandanencephaly
FolateprotectsagainstNTDs
Neural Tube DefectsHoloprosencephaly
Neural Tube DefectsHoloprosencephaly
Lecture overviewEarly Development of the Ectoderm
Gastrulation and Embryonic Folding
Neurulation
Early Development of the Nervous System
Neural Crest
Epidermis Development
Ectodermal placodes
Neural Tube Defects
DrAnnemiekBeverdam– SchoolofMedicalSciences,UNSWWallaceWurth BuildingRoom234– A.Beverdam@unsw.edu.au
Resources:http://php.med.unsw.edu.au/embryology/
Larsen’s Human EmbryologyThe Developing Human: Clinically Oriented Embryology
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