Cours: Neurogenesis and Development

Neurogenesis Overview

• Neurogenesis is the process of neuronal development
• Stages: Proliferation, Differentiation, migration, axon pathfinding, synapse formation, circuit formation, maturation, cell death, and pruning.
• Key stages are listed in their specific order of occurrence in development, and in the context of the neural tube.

Proliferation

• Cell multiplication is the primary process of proliferation
• Stem cells multiply, a key aspect of neurogenesis

Gastrulation

• Gastrulation is a critical process that produces the three germ layers (ectoderm, mesoderm, and endoderm) in a developing embryo, including avian and amphibian embryos.
• Key features include cleavage furrow, blastoderm, yolk area opaca and pellucida, cleavage furrow, blastula, and early and late gastrula stages.
• Three germ layers and their origins are key to gastrulation

Neurulation

• Neurulation, following gastrulation, generates the neural tube.
• The neural plate folds into a neural groove, and eventually fuses to form a tube, which will develop into the central nervous system (CNS).

Embryonic Development in Chicken Embryos

• Chicken embryos are useful models for studying embryonic development due to their accessibility within the egg.
• Key developmental landmarks, such as brain, heart, eyes, wing buds, leg buds, and tail buds can be identified.

Neural Development as Default Pathway

• Cell dissection highlights that neuronal development is the default outcome for cells in the early embryo in the absence of cues to direct cell fate.
• BMP proteins and bone morphogenic proteins are critical to this default pathway

Timing in Development

• Developmental timing is crucial, and developmental processes are highly regulated.
• Specific periods in development, such as pregastrula and gastrula stages are key in specifying cell fate.

Neural Development is the Default Pathway

• Neural development is the initial trajectory of specific cell groups

Lateral Inhibition Defines Number of Neural Precursor Cells

• Lateral inhibition is a cell signaling process that accurately determines the number of cells adopting a specific neural progenitor cell lineage.
• This process plays a role in limiting the amount and type of cell lineages that form.

Notch Signaling

• Notch signaling regulates cell fate decisions.
• In particular, it regulates proliferation and differentiation outcomes of precursors

Hox Genes and Compartments

• Hox genes establish compartments along the anterior-posterior axis during development.
• These genes are highly conserved, meaning their function and structure is similar across species, including animal models that have been used to understand mammalian development.

Patterning the Nervous System and Longitudinal Axis

• The longitudinal axis and patterning of the nervous system are organized by Hox genes and their expression patterns.
• Specific structures along the longitudinal axis and their positions are specified by particular gene expression and location.

Cranial Nerves

• A list of cranial nerves and their functions are included

Compartments and their Boundaries in Vertebrate Brain Development

• Boundaries during brain development and compartments are regulated

Organization of the Longitudinal Axis

• Hox gene expression patterns dictate organization along the longitudinal axis
• Specific Hox gene expression patterns occur in a particular order from anterior to posterior, resulting in organization and structure along the longitudinal axis.

The Notochord

• The notochord is a transient mesoderm structure.
• It is significant for patterning the neural tube during development

The Notochord is Required to Induce the Floor Plate

• The notochord is essential for inducing the floor plate.
• The notochord's absence or manipulation can lead to abnormalities in floor plate formation.