What are neural crest cells?
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Multipotent stem cells.
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What are neural crest cells?
Multipotent stem cells.
What process do neural crest cells undergo from the dorsalmost neural tube?
Neural crest cells undergo EMT (epithelial-mesenchymal transition) from the dorsalmost neural tube.
How do radial glial cells assist in neuronal migration?
They serve as the scaffold for the migration of other progenitor cells and newborn neurons.
How do cranial neural crests migrate?
As streams.
What signaling mechanism attracts neural crest cells in the chase and run model?
SDF1 - CXCR4 signaling.
What can trunk neural crest cells generate?
Neurons, glia, and melanocytes.
What do cardiac neural crest cells develop into?
Cardiac neural crest cells develop into neurons, cartilage, and connective tissue of the heart.
What is primary neurulation?
Cells surrounding the neural plate direct the neural plate cells to proliferate, invaginate into the body, and separate from the surface ectoderm to form an underlying hollow tube.
Which rhombomere contributes to Pharyngeal arch 2?
Rhombomere 4 (r4).
Where do neurons born earlier form in the brain?
In the deeper layers closer to the ventricle.
Where do committed donor neurons go?
To their presumptive layer.
Where do retinal ganglion cells project with regional precision?
To the optical tectum.
What is address selection in axon guidance?
The initial pattern is refined such that each axon binds to a small subset (or just one) of its possible targets.
What does the dorsal-ventral axis refer to in neuroanatomy?
The dorsal-ventral axis refers to the back (dorsal) to belly (ventral) orientation in the body or an organism.
What is neurogenesis?
The process of generating new neurons in the brain.
What is the role of Cajal-Retzius cells in the brain?
They lie under the pial surface and secrete Reelin to regulate layering in the brain.
What can bipotential neuromesodermal progenitors (NMPs) develop into?
Either posterior neural tubes or somites.
What type of gradients are present in the retina for Ephrin receptors?
Nasal - Temporal gradients.
What happens when there is a low concentration of Ephrin receptors in the retina?
It causes repulsion at higher concentrations of Ephrin, leading to projection to Ephrin-high, posterior regions of the tectum.
What is the first step in axon guidance during neuronal differentiation?
Pathway selection, where axons travel along a route to a particular region of the embryo.
What role does Snail2 play in neural crest migration?
It downregulates N-cadherin and E-cadherin.
Which receptor is associated with Isl2 and Lim1, and where do these axons project?
EphA4 (receptor for ephrin 5A), projecting to dorsal limb muscle.
What does the anterior-posterior axis refer to in neuroanatomy?
The anterior-posterior axis refers to the front (anterior) to back (posterior) orientation in the body or an organism.
Which rhombomeres contribute to Pharyngeal arches 3 and 4?
Rhombomeres 6 to 8 (r6 - 8).
What type of progenitors are found in the posterior region of the neural tube?
Bipotential neuromesodermal progenitors (NMPs).
What happens to Disabled-1 signaling close to the pial surface?
Disabled-1 signaling is inhibited, ending migration and enabling differentiation into specific neuron types.
Which receptor is associated with Isl1 and Isl2, and where do these axons project?
Neuropilin-2 (Sema-3F receptor), projecting to ventral limb muscle.
What type of guidance cues are Sema-3F and Ephrin A5?
Repellent guidance cues.
What do the six layers of the neocortex contain?
Different types of neurons.
What does Reelin signaling activate and induce?
Reelin signaling activates Disabled-1 and induces N-cadherin expression.
What gradient do neurons follow to migrate towards the pial surface?
Neurons follow the N-cadherin gradient to migrate towards the pial surface.
What role do radial glial cells play in the central nervous system?
They are major neural stem cells that give rise to both neurons and glial cells.
What proteins stabilize microtubules (MTs) upon encountering attractive cues?
CLASP and APC stabilize microtubules upon encountering attractive cues.
What is secondary neurulation?
The neural tube arises from the aggregation of mesenchyme cells into a solid cord that subsequently forms cavities that coalesce to create a hollow tube.
On what do neural precursor cells migrate to form new layers in the neocortex?
Radial glial processes.
What fate do progenitors in the anterior region of the neural tube adopt directly from the epiblast?
A proneural fate.
What do medial retinal ganglion cells (RGCs) express that allows them to cross the chiasm?
DCC but no EphB1 (Ephrin B2 receptor).
Which molecules help in neuronal migration?
F-actin and Integrin help in neuronal migration.
What happens to F-actin and microtubules (MTs) upon encountering repulsive cues?
F-actin and microtubules disassemble upon encountering repulsive cues.
What do trunk neural crest cells develop into?
Trunk neural crest cells develop into sensory neurons of the dorsal root ganglia.
What triggers the expression of Snail2 during neural crest migration?
BMP and Wnt signaling.
What condition results from the failure to close the anterior neuropore?
Anencephaly, which is often lethal.
Name some repellent guidance cues for retinal ganglion cell axons.
Chondroitin sulfate, Semaphorin, Slit1/2, Ephrin B2.
What is the function of filopodia in the growth cone?
Filopodia are sensory structures that help the growth cone sense its environment.
What do cranial (or cephalic) neural crest cells develop into?
Cranial neural crest cells develop into cartilage, bone, cranial neurons, glia, pigment cells, connective tissue of the face, and bones of the middle ear and jaw.
What type of gradients are present in the tectum for Ephrin ligands?
Anterior - Posterior gradients.
What is the incidence of neural tube closure defects in human live births?
About 1 in every 1000 live births.
At what point do neural crest cells delaminate?
Neural crest cells delaminate at the point of neural tube closure.
What is the role of Slit in neuronal development?
Slit acts as a repulsive guidance cue to prevent axons from recrossing the midline.
What happens during the target selection phase of axon guidance?
Axons recognize and bind to a set of cells to form stable connections.
What directs the movement of retinal ganglion cell axons to the optical tectum?
Multiple guidance cues.
What is the function of ventricular cells?
They form the neural tube lining and secrete cerebrospinal fluid (CSF).
What are the two key molecules involved in crossing the midline in neuronal development?
Netrin and Slit.
What does WT stand for in the context of genetic studies?
WT stands for Wild Type, referring to the normal, non-mutated genotype.
What condition results from the failure of the entire neural tube to close over the body axis?
Craniorachischisis.
How many layers does the neocortex stratify into?
Six layers of neuronal cell bodies.
How does a multipotent neural crest cell refine its developmental potential?
By dividing and progressively refining its developmental potential.
What happens when there is a high concentration of Ephrin receptors in the retina?
It causes repulsion at lower concentrations of Ephrin, leading to projection to Ephrin-low, anterior regions of the tectum.
What is the role of N-cadherin in collective migration of neural crest cells?
Low levels of N-cadherin facilitate collective migration.
What condition results from the failure to close the posterior neuropore?
Spina bifida.
What do neural crest cells do after delaminating from the epithelia?
They migrate away to form other cells.
What do cranial neural crests form?
Most of the face.
What defines the anterior-posterior (A-P) and dorsal-ventral (D-V) axes in neural development?
Opposing morphogens.
What is the role of the growth cone in axonal pathfinding?
The growth cone is responsible for the migration of the axon.
What do neuroepithelial cells differentiate into?
Ventricular cells and radial glial cells.
What structures do neural crest cells form?
Neural crest cells form the facial skeleton, pigment cells, and the peripheral nervous system (PNS).
What regulates the differentiation of neural crest cells?
Paracrine factors in the local environment.
What mediates contact inhibition during neural crest migration?
Rho GTPases and cytoskeletal remodeling.
What is the function of MHP cells in neural tube formation?
MHP cells are anchored to the notochord and form a hinge that enables the creation of a furrow.
What occurs during neural tube closure?
Neural and surface ectoderm cells from one side fuse with their counterparts from the other side, and cells at the apex of the neural folds delaminate to become neural crest cells.
From where do neural crest cells delaminate?
From the epithelia at the dorsal midline.
From where do neural precursor cells migrate to form the neocortex?
From the mantle zone.
What is an example of an attractant guidance cue for retinal ganglion cell axons?
Netrin.
What can cranial neural crest cells generate?
Neurons, glia, melanocytes, cartilage, muscle, bone, and connective tissues.
Which molecules act as chemorepellents to keep streams of cells apart in the chase and run model?
Semaphorin and ephrin.
What is the role of Netrin in neuronal development?
Netrin acts as an attractive guidance cue for axons to cross the midline.
How do polarized cells enable movement during neural crest migration?
By retracting on one side (high RhoA) and extending on the other side (high Rac1).
What type of guidance cues are FGFs?
Attractive guidance cues.
What is the result of failed separation of neural and surface ectoderm?
Neural tube closure defects.
What happens to cells at the apex of the neural folds during neural tube closure?
They delaminate and become neural crest cells.
What does 'building from the bottom up' refer to in neurogenesis?
It refers to the sequential development of neurons starting from the innermost layers of the brain and progressing outward.
What role do Rho GTPases play in cellular signaling?
Rho GTPases interpret and relay external guidance signals to the actin cytoskeleton.
Which regions of the brain contribute to Pharyngeal arch 1?
Midbrain and rhombomere 1, 2.
What happens to axonal guidance in the presence of a Slit mutation (Slit(-))?
Axons may fail to be repelled after crossing the midline, leading to abnormal recrossing.
Which receptor is associated with Isl1, Isl2, and Lhx3, and where do these axons project?
Receptor for FGFs, projecting to the dermomyotome.
What facilitates the fusion of neural and surface ectoderm during neural tube closure?
Matching cadherin expression.
How does a deficiency in folate or folic acid (Vitamin B9) lead to neural tube defects?
It leads to changes in the epigenetic regulation of embryos, altering gene expression patterns.
What causes placode cells to migrate away in the chase and run model?
Contact inhibition.
What is the function of lamellipodia in the growth cone?
Lamellipodia are motile structures that help in the movement of the growth cone.
What do uncommitted donor neurons do?
They follow the host neurons.
What attractive signal is secreted during the collective migration of neural crest cells?
Complement 3a (C3a).
What role do DLHP cells play in neural tube formation?
DLHP cells are anchored to the epidermal ectoderm, allowing the convergence of neural folds.
What is the significance of apical restriction in MHP and DLHP cells?
Apical restriction helps in the proper formation and convergence of neural folds.
What maternal environmental factors can contribute to neural tube defects?
Diet, folate levels, cholesterol, diabetes, obesity, drugs, and toxins.
What does the vertebrate ectoderm give rise to?
The nervous system and epidermis.
