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Questions and Answers
What is the significance of the Spemann-Mangold organiser in developmental biology?
What is the significance of the Spemann-Mangold organiser in developmental biology?
Which of the following correctly describes how morphogens influence cell fate?
Which of the following correctly describes how morphogens influence cell fate?
What is one potential consequence of improper morphogen gradients, particularly involving Shh?
What is one potential consequence of improper morphogen gradients, particularly involving Shh?
What are the key processes involved in neural circuit construction during development?
What are the key processes involved in neural circuit construction during development?
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Which statement best describes the role of transcription factors in relation to morphogens?
Which statement best describes the role of transcription factors in relation to morphogens?
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What role do radial glia play in the building of the cortex?
What role do radial glia play in the building of the cortex?
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Which statement accurately describes the process of migration in cortical development?
Which statement accurately describes the process of migration in cortical development?
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What do glioblasts become when they move to the marginal layer?
What do glioblasts become when they move to the marginal layer?
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How is the origin of cortical interneurons different from that of other neurons?
How is the origin of cortical interneurons different from that of other neurons?
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What characterizes the columnar organization observed in the cortex?
What characterizes the columnar organization observed in the cortex?
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What is the importance of a highly ordered structure in neuron axon extension?
What is the importance of a highly ordered structure in neuron axon extension?
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What role do cues or signals play in the navigation of growing neural processes?
What role do cues or signals play in the navigation of growing neural processes?
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Which of the following correctly describes the process of fasciculation in neural growth?
Which of the following correctly describes the process of fasciculation in neural growth?
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What describes the initial phase of neurite formation?
What describes the initial phase of neurite formation?
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What factors are crucial for successful synapse formation?
What factors are crucial for successful synapse formation?
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Study Notes
Brain Development and Construction of Neural Circuits - II
- Course title: BIOL2051-52
- Lecturer: Kif Liakath-Ali, PhD
- Email: [email protected]
- Website: www.splicelab.co.uk
Learning Outcomes - Last Week
- Students should be able to describe the processes of neurogenesis, differentiation, and migration.
- Students should be able to describe the process of target innervation.
- Students should be able to describe the principles of synapse formation and elimination.
How Do We Know That Cell Fate Can Be Induced?
- Grafting tissue from pigmented to non-pigmented amphibian embryos can induce a secondary axis in the recipient embryo.
- Transplanted cells from the donor embryo influence the host cells.
- The Spemann-Mangold organiser (1923) led to the Nobel Prize for Hans Spemann in 1935, showcasing the ability of cells to induce changes in the development of other cells.
How Morphogens Act?
- Morphogens bind to receptors, activating or repressing sets of transcription factors.
- Transcription factors control gene expression programs.
- Gene expression profiles determine cell identity.
- The distance from the secreting cells (gradients), ligand availability, and receptor presence dictate the response of each cell.
What Happens If Gradients Go Wrong?
- Lack of Shh can lead to optic vesicles forming on the dorsal side instead of the ventral side.
- Loss of Shh inhibition causes a loss of ventral identity.
- This can result in synophthalmia (cyclopia).
Learning Outcomes - Today
- Students should be able to describe the processes of neurogenesis, differentiation, and migration.
- Students should be able to describe the process of target innervation.
- Students should be able to describe the principles of synapse formation and elimination.
How Do Neurons Get Into Their Correct Place? Example: Building the Cortex
- This section discusses neuronal migration, focusing on cortex development.
Differentiation and Migration: Building the Cortex
- Neuroepithelium/Neuroepithelial progenitor cells differentiate into neural precursor cells within the neural tube.
- These cells form the ventricular zone.
- Radial glia connect the ventricular and pial surfaces and divide slowly and symmetrically.
- Precursor cells divide asymmetrically in the ventricular zone (innermost layer of the neural tube), creating "transit amplifying cells".
- These cells generate new progenitors and postmitotic neuroblasts.
Asymmetric and Symmetric Divisions
- Asymmetric divisions lead to neurogenesis.
- Symmetric divisions give rise to proliferative divisions.
Migration
- Neuroblasts migrate to the pial surface, forming the marginal zone.
- Newer neuroblasts migrate past older neurons.
- Cortex development occurs from "inside out".
- Neuronal final location reflects birthdate and contributes to columnar organization.
Not Just Neurons: Origin of Glia
- Glial cells originate from neuroepithelium.
- Glioblasts can remain attached to the lumen, becoming ependymal cells (generating CSF).
- Glioblasts can migrate to the marginal layer, differentiating into astrocytes (maintenance and repair) or oligodendrocytes (myelination).
Migration in Action
- Supplementary movie 5 showcases EGFP-expressing neurons imaged from E15 + 3DIV
- Imaging occurred over 8 hours and 48 minutes.
Developing Cortex
- Images and anatomical details of early cortex development stages in human embryos
Cortical Interneurons Have A Different Origin!
- Interneurons originate in the ganglionic eminences.
- Interneurons migrate tangentially.
Early Development - Summary
- Embryonic development stages, highlighting neural plate formation.
Now that Neurons are Specified and in Their Correct Place, How to Form a Network?
- This section transitions to the next stage of neuronal development, where neural networks form.
Learning Outcomes - Today
- Students should be able to describe the processes of neurogenesis, differentiation, and migration.
- Students should be able to describe the process of target innervation.
- Students should be able to describe the principles of synapse formation and elimination.
Polarisation
- Neurites (axons and dendrites) grow out.
- Axon and dendrites establish in a process with five stages.
Target Innervation
- Brains need proper wiring to function.
- Axon extension may be random.
- Brain function depends on highly ordered neural circuits.
- Growing processes follow cues and stepping stones in their migration.
- Processes piggyback along pathways (fasciculation).
How Do Axons Find Their Correct Target?
- A London underground map visually represents the intricate process of axon target seeking in the brain.
Learning Outcomes - Next Time
- Students will be expected to describe the processes of neurogenesis, differentiation, and migration.
- Students will be expected to describe the process of target innervation.
- Students will be expected to describe the principles of synapse formation and elimination.
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Description
This quiz focuses on advanced topics in brain development, including neurogenesis, synapse formation, and the principles of cell fate induction. Students will explore the processes of differentiation, migration, and target innervation. Prepare to delve into the intricacies of neural circuit construction and morphogen action.
