Neurodevelopment Flashcards by Wynter Dragone

Morula is the solid ball fo cells formed as the zygote undergoes ???

cleavage

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early or late (?) blastocyst is a hollow ball of cells with a fluid-filled caivty

early blastocyst

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early or late (?) blastocyst is pre-embryo with embryonic disk, two layers of cells that become the embryo proper

late blastocyst

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primary germ layers: the ectoderm gives rise to ???

skin and nervous tissue

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gastrula is the embryo with ??? primary germ layers

3 primary germ layers

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primary germ layers: the endoderm gives rise to ???

viscera

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primary germ layers: mesoderm gives rise to ???

muscles and bones

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Neurulation occurs at ??? gestational days

~22 days

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Neurulation: a longitudinal band of ??? thickens to become the neural plate

ectoderm

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differential division rates cause upward folding of plate to become ??? –> neural tube

neural fold

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lateral border of the neural fold becomes the neural ???

crest

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the neural tube later forms into the ???

CNS

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dorsal ectoderm of gastrual forms ???

neural groove

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if the neural tube does not close together, this causes neural tube defects. i.e. anencephaly due to failure of ANTERIOR or POSTERIOR neuropore to close?

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Anencephaly: brain is not formed, ??? may be absent, facial abnormalities, neonatal death is inevitable.

skull

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failure of ANTERIOR or POSTERIOR neuropore to close = spina bifida

posterior

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Spina Bifida is a condition in which malformations of the spinal cord occur, characterised by failure of one or more ??? arches to meet and fuse

vertebral

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Spina Bifida Occulta or Cystica is when spinal cord + meninges are unharmed and remain within the vertebral canal. Common site = lumbosacral area, and usually associated with no disturbance of neurological or musculoskeletal functioning

Pina Bifida Occulta

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SB Cystica, Meningocele or Myelomeningocele: Cystic protrusion of meninges and CSF through defective vertebral arches. Spinal cord remains in the vertebral canal. May still exhibit some abnormalities. Clinical signs vary or may be absent

Meningocele

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SB Cystica, Meningocele or Myelomeningocele: Majority of SB cases. Cystic protrusion of spinal cord, meninges and CSF through defective vertebral arches. Open myelomeningocele: nerve roots and spinal cord may be exposed

Myelomeningocele

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SB complications include:
- ??? ‘water on brain’
- spinal tethering
- Chiari Malformation

hydrocephalus

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chiari malformation ocurs when brainstem and/or cerebellum is pushed down through opening of brain, compressing the brainstem, lower cerebellum = obstruction of ??? flow

CSF.
note: this is also known as tonsillar herniation

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Syringomyelia/ Syringobulbia = fluid filled cyst (syrinx)
this is a complication of ???

SPina Bifida

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Folic acid is essential for synthesis of ??? i.e. when cells divide

DNA/RNA

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??? deficiency is a risk factor for neural tube defects.

Folic Acid

the ??? is a neural inducer that is made of mesodermal tissue and sits under the neural plate

notochord

the notochord arise at ~16 gestational days, and is ??? (i.e. not in adults)

transient

Notochord activates/ represses developmental (homeobox) genes (transcription factors) in the ???

neural plate

the ??? stimulates synthesis of growth fators that are produced in a gradient, causing differential growth rates of neural tissue

notochord

the ectoderm produces ??? protein which, early in development, inhibits the formation of neural tissue

bone morphogenetic protein

the notochord releases ??? and cordin which inhibit bone morphogenetic protein and induce neural tissue

noggin

the notochord releases sonic hedgehog, a growth factor which causes a dorsal ventral separation of the neural tube and induces ??? neuron formation

motor neuron

when released in a gradient from ROOF PLATE of neural tube or ECTODERM (?), bone morphogenetic protein induces dorsal sensory neuron formation

ROOF PLATE of neural tube

Sonic Hedgehog is secreted in a gradient from the ??? of the neural tube to induce motor neuron differentiation

roof plate

Notochord induces the spinal cord to be separated dorso-??? separation is functional for gray matter of entire cord and brianstem.

ventrally

??? induces separation of spinal cord into alar plate dorsally: basal plate ventrally

notochord

A nuclei is a collection of cell bodies in the ??? (as opposed to a ganglia in the PNS)

CNS

In the brainstem we have cranial nerve NUCLEI or GANGLIA?

NUCLEI

Alar/basal plate is in the dorsal/ventral orientation in t lower ??? and midbrain

medulla

Alar/basal plate is in a lateral/medial orientation in upper medulla and ???, due to fourth ventricle

pons

Motor cranial nerve nuclei are located ??? in the lower medulla and midbrain, but are located medially in the upper medulla and pons

ventrally

Sensory cranial nerve nuclei are located ??? in the lower medulla and midbrain but are located laterally in the upper medulla and pons.

dorsally

prosencephalon/ forebrain is more ROSTRAL or CAUDAL during development?

ROSTRAL

Mesencephalon/midbrain is more ROSTRAL or CAUDAL during development of brain?

neither, it is in the middle portion

Rhombencephalon/ hindbrain is more ROSTRAL or CAUDAL during development of brain?

Caudal

the forebrain develops into the telencephalon and ??? which then develop into cerebral hemispheres and the thalamus respectively

diancephalon

the hindrabin develops into the metencephalon and ??? which develop into the pons + cerebellum and the medulla respectively

myelencephalon

the caivty in the neural tube becomes the ??? system and changes shape with different growth rates

ventricular

TRUE or FALSE: Expansion of cerebrum is not uniform

TRUE

flexures during development result in 'tipping' brain 90 degrees. occurs at 3 OR 5 vesicle stage?

3-vesicle stage

Retinoic Acid is a Vitamin A derivative that induces hindbrain (i.e brainstem/ cerebellum) and ANTERIOR or POSTERIOR cord development

TRUE or FALSE: very few neurons can be replaced because precursor cells tend to disappear

TRUE

There is evidence for neurogenesis in the ault brain, particularly in the subventricular zone, the hippocampus and the ???

amygdala

stem cell lines from neurodevelopment for: new stem cells, neurons, glial cells (neurons and ??? are generated first, oligodendrocytes are generated last)

astrocytes

daughter cells made from stem cels migrate out of the ventricular zone into the ???

mantle

ventricular zone: ependymal cells (stem cells for ??? and neurons, new cells migrate away)

glia

Marginal zone: few cell bodies, fibres of neurons in ??? extend out to marginal. Cajal-Retzuis cells are transiently located here

mantle

Interkinetic nuclear migration 1. Cell in the ??? zone extends process upward toward pial surface

ventricular

Interkinetic nuclear migration 2. Cell nucleus migrates upward toward ??? surface ‐> cell’s DNA is copied

pial

Interkinetic nuclear migration 3. Nucleus containing two copies of the DNA ‐‐> ??? surface. 4. Cell retracts its arm from the pial surface 5. Cell divides into two

ventricular

VERTICAL or HORIZONTAL cleavage (ie symmetrical division) = precursor daughter

Vertical

VERTICAL or HORIZONTAL cleavage (ie asymmetrical division)= daughter migrates away

Horizontal

Neuronal Migration: Radial glia arms provide a pathway for cell migration from ??? zone to mantle

ventricular zone

Adult cerebral cortex has 6 cell layers containing different types of cells. Migration of these layers occurs in an orderly, inside-out fashion. Layer 6 migrates ???; Layer 5 migrates thru Layer 6; Layer 4 moves thru layer 6 & 5, etc.

first

Neuronal migration in cerebral cortex: Fate of neuroblast depends upon environmental condition. Axons, ??? & connections don’t become established until neuroblast reaches its destination

dendrites

in neuronal migration in cerebral cortext, do the subplate cells or cortical neurons migrate first?

subplate, and THEN cortical

Reelin is a glycoprotein that is released from Cajal–Retzius cells in the outer marginal zone. It binds to receprots to guide termination of migration and organise proper neuronal ???

layering

Reelin gene mutations in humans produce disruptions in neuron ??? and connectivity, lissencephaly and cerebellar hypoplasia.

migration

Cortical pyramidal neurons and astrocytes are found in the ??? zone of the dorsal telencephalon. Have Radial migration

ventricular zone

Inhibitory interneurons and oligodendrocytes are sourced in the ventricula zone of the VENTRAL or DORSAL telencephalon. Have tangential migration

Ventral

synaptogenesis: When neurons differentiate, they not only need to form axons and dendrites, but also the axons must find their appropriate ???

targets

Neuroblast migrates and THEN differentiates, extending its processes i.e. neurites that will ultimately become axons and ???

dendrites

growth cone refers to the growing tip of a ???

neurite

Growth cone is specialised to identify an appropriate path for neurite ???. Filopodium takes hold of the surface in which it is growing and pulls the advancing growth cone forward

elongation

‘Integrins’ of the growth cone bind to ??? molecules on the extracellular matrix to promote forward movement of growth cone/axon

laminin

Fasciculation: Bottom axon grows along molecular highway of ECM. Other axons piggy back, stick together via cell ??? molecules (CAMs)

cell adhesion molecules

TRUE or FALSE: growth cones differ in the molecules they express on their membranes. this helps with axon guidance

TRUE

Interaction of cell surface molecules with guidance cues help determine the direction and amount of growth of the ???

growth cone

axon guidance includes molecules such as chemoattractants and chemo???

chemorepellents

Myelination begins at ~6 months of gestation and continues into adulthood. Motor and ??? tracts throughout NS mature early, whereas the association tracts develop relatively late

sensory

critical periods are time periods during development when the NS must obtain certain critical experiences such as ??? to develop properly

sensory, movement or emotional input

After a critical period, connections DIMINISH or GROW in number, are less subject to change, and are stronger, more reliable, and more precise

diminish

Amblyopia: Vision in one of the eyes is ??? because the eye and the brain are not working together properly. * Often caused by Strabismus = Incorrect alignment of the eyes

reduced