Neurulation And Nervous System Flashcards
What is neurulation?
Formation of neural tube and early CNS development
What is the neural crest?
Formation of the PNS (among other products)
During what days does embryonic disc transition from bilaminar to trilaminar?
14-16
What two things happen in order for embryonic disc to transition from bilaminar to trilaminar?
Days 14-15: epiblast cells dive through primitive streak, invading hypoblast and form the secondary endoderm
Day 16: more epiblast cells dive through primitive streak and form a new 3rd layer (mesoderm)
Formation of a trilaminar embryo eventually leads to what ?
Neurulation and formation of the neural tube and neural crest
Trilaminar disc lies between what two things?
Amniotic cavity and chorionic cavity
What parts of the body do the following germ layers produce
- Ectoderm
- Mesoderm
- Endoderm
- Nervous system (via neurulation) and skin
- Bones, muscle, urogenital organs, mesothelial linings, cardiovascular system
- GI tract, airway
- When do the prechordal plate and notochordal process form and how?
- General location of prechordal plate
- What do notochordal process and prechordal plate form and what is this products function
- Day 17– another wave of ingressing epiblast cells dive through primitive pit
- Further cranially
- Notochord= gives rise to vertebral bodies and induces ectoderm to form neural tube and neural crest
- What are the three plates that the mesoderm splits into?
- What do each of these plates form?
- Where is notochordal process located?
- Paraxial, intermediate and lateral
- Paraxial- axial skeleton, skeletal muscle and part of dermis
Intermediate- urogenital systems
Lateral- most of dermis and lining of body wall; linings of visceral organs - At midline, in between these structures (like in between both sides)
When the notochordal process fuses with endoderm, it does so in what direction
Notochordal process becomes the ___ which then becomes the ___
Commences at caudal end and proceeds cranially
Notochordal plate —> notochord
What does rostral mean
Cranial
Prechordal plate and notochordal process induce ectoderm to form ____. How do they do this?
Neural plate (which differentiates into the CNS) By secreting signals
Somites are derivatives of?
Where are they located
What do they help make
Paraxial mesoderm
Just lateral to neural tube
Vertebral column
Neural tube is filled with
Amniotic fluid, later replaced by CSF
~neural tube is what the neural plate becomes
3 zones of neural tube from exterior to interior
Which zone do neuroepithelial cells undergo mitosis? What forms?
Marginal zone, mantle zone, and ventricular zone
Ventricular zone; forms glioblasts and neuroblasts
- What are neuroblasts?
2. What are glioblasts?
- Stem cells that form neurons
2. Form glial cells (ependymal and radial glia cells)
- Which plate yields sensory regions of spinal cord?
- Motor regions?
- Where do autonomics develop?
- Alar plate
- Basal plate
- Sulcus limitans (kind of centrally located)
What is anencephaly and why does it occur?
Failure of entire brain to develop; nerve pores don’t close so brain development does not continue (very small skull)
Explain the following of types of herniations that occur due to problems with closure of the skull:
- Meningocele
- Meningoencephalocele
- Meningohydroencephalocele
- Herniation of meninges
- Herniation of meninges and brain tissue
- Herniation of meninges, brain tissue and ventricle
Difference between spina bifida cystica and spina bifida occulta
Cystica= herniation of just meninges or meninges and spinal cord into a cyst covered by skin
Occulta= no herniation or formation of cyst; failure of closure of spinal canal but back appears normal
What are somites?
What are somites derived from?
What do they subdivide into?
Mature somitomeres
Paraxial mesoderm
Sclerotomes (produce bones) and dermamyotome (dermis and muscles)
7 most cranial somitomeres produce what?
How many caudal somites form axial skeleton?
Muscles of face, jaw, and pharynx (CN 5,7,9,10)
34
Location of somites?
What do somites form?
On each side of neural tube; just lateral to somites is intermediate mesoderm, and lateral to that is lateral mesoderm
Axial skeleton, ribs, some cranial bones, skeletal muscle and part of dermis
IVD if formed from what?
IVD comes from pieces of sclerotome and notochord: sclerotome= annulus fibrosus; notochord= nucleus pulposus
Axons are developed from?
Developing motorneurons in spinal cord extending processes through developing vertebrae to myotomes
Location of neural crest?
Neural crest forms what structures?
Neural tube forms what structures?
Between ectoderm and neural tube
All components of PNS, cranial nerve ganglia, adrenal medulla, arachnoid and pia mater, and enteric nervous system
Spinal cord and brain
Where do placodes derive from?
Significance of placodes?
Ectoderm (placodes are structures outside of neural tube)
Neural crest cells migrate to join the placodes and form sensory neurons and parasympathetic neurons (post-ganglionic)
Neural tube has two ends and what in the middle
Cranial and caudal with neural crest cell differentiation in the middle
When looking at the caudal end of the neural tube, it has 3 layers. Name them from superficial to deep
Marginal zone, mantle zone, and neuroepithelial zone
What else is formed from caudal end
Alar (dorsal) and basal (ventral) plates
