Neurulation and PNS formation Flashcards
What is Neurulation?
Folding process in vertebrate embryo;
Neural plate -> neural tube
What is the new ectoderm comprised of?
Neuroectoderm and surface ectoderm
What does the notochord cause to form in the neuroectoderm?
Neural plate in week 3
What do you need the notochord for?
Neurulation and nervous system development
What happens in primary neurulation?
Neural plate –> Neural folds –> Neural tube
Where does neurulation start?
5th somite
What is the neural groove?
Center of neural plate right above the notochord that holds in place so the neural folds can fold
What happens when the neural folds enlarge and fold up?
They eventually fuse and pinch off to form neural tube
What are the lateral most cells from the neural plate called?
Neural crest cells ;
They fuse as well in between the surface ectoderm and neural tube and will eventually migrate away
What layer of the primary germ layers forms the neural tube?
Ectoderm
What and where are the 2 neural pores?
Cranial neuropore and caudal neuropore - last things to close
Neural tube closes around what?
Up and around the head and down to the 31st somite
What marks the end of primary neurulation?
Closure of cranial and caudal neuropores
What marks the end of gastrulation?
Formation of tail bud (caudal eminence)
What is secondary neurulation?
Formation of neural tube from tail bud
Describe what happens during secondary neurulation
Tail bud cells condense into medullary cord
Medullary cord cavitates and creates a lumen
The medullary cord then merges with the central canal of the neural tube
What are neural crest cells?
Neuroectodermal cells along dorsal side of neural folds that run along entire cranial-caudal neural tube
Where do the neural crest cells go?
Migrate VENTRALLY using EMT and give rise to many derivatives
List some things neural crest cells create
Create jaw, pulmonary trunk and pigment cells
Abnormalities in NCC are called
Neurocristopathies
What develops the meninges?
NCC and mesenchyme that migrate and surround neural tube to form meninx primitiva
20-35 days
What does the meninx primitiva create?
Ectomeninx and endomeninx
What then happens to the ectomeninx?
It forms spaces for venous sinuses and then dissociates to create the epidural space
The ectomeninx ultimately becomes
The dura matter
