Nervous System Development and Structure

Nervous System Development

• Neuroblast is part of CNS & PNS development
• Signaling proteins influence development
  • BMP4 from surface ectoderm
  • Sonic hedgehog (Shh) from notochord
  • Hepatic Nuclear Factor-3β from developing notochord
  • Noggin
  • Cordin
  • BMP4 prevents dorsal ectoderm from forming neural tissue
  • Sonic hedgehog is a chemical signal essential for embryonic development
  • Noggin and Cordin block BMP4's influence, allowing neural tissue formation

Nervous System Structure

• Nervous system has central (CNS) and peripheral (PNS) components
• Diagram shows horse nervous system with spinal cord, brachial plexus and lumbosacral plexus. Major nerves are identified: femoral, radial, sciatic, ulnar, median, peroneal, palmar and tibial.

Signaling Proteins in Development

• BMP4 influences development, preventing neural tissue formation in the dorsal ectoderm.
• Sonic hedgehog (Shh) is an important chemical signal crucial for embryonic development.
• Noggin and Cordin block BMP4, promoting the formation of neural tissue.

Neuroblast Formation

• Neuroblasts migrate from the neuroepithelium into the developing mantle layer.
• Neuroblasts transform into bipolar cells with an axon and dendrite.
• The single dendrite typically degenerates, and multiple dendrites develop.
• Neuroblasts that don't form functioning connections degenerate.

Cell Lineages of the CNS

• Neuroepithelium gives rise to various cell types
  • Neurons develop from neuroblasts.
  • Astrocytes and oligodendrocytes are glial cells.
  • Microglia are phagocytic cells derived from the mesoderm.
  • Ependymal cells line the ventricles and central canal.
• Glial cells of the spinal cord originate from neuroepithelium.
• Microglia are derived from mesoderm.
• Glial cells are located in both peripheral and central nervous systems.
• Satellite and Schwann cells are part of the PNS.
• Oligodendrocytes and astrocytes are part of the CNS.
• Ependymal cells create and monitor cerebrospinal fluid.
• Microglia are immune cells, removing debris and pathogens.

Nervous System and Glial Cells

• Glial cells support and protect neurons.
• Schwann cells form myelin sheaths in the PNS.
• Oligodendrocytes form myelin sheaths in the CNS.
• Astrocytes support neuronal function and maintain the blood-brain barrier
• Microglial cells act as immune cells, removing waste and pathogens.
• Different types of glial cells have distinct functions.

Spinal Cord Development

• Ependyma and ventricular system are part of spinal cord development
• Spinal cord has distinct zones: Ventricular, intermediate zone, and marginal zone.
• The roof and floor plates of the spinal cord develop into dorsal and ventral structures.
• Basal plates contain general somatic and visceral efferent nerve fibers
• Alar plates contain general somatic and visceral afferent nerve fibers.
• Spinal cord development involves the formation of dorsal and ventral horns

Brain Development

• The prosencephalon (forebrain) gives rise to the telencephalon and diencephalon
• The mesencephalon (midbrain) develops into parts of the brain
• The rhombencephalon (hindbrain) differentiates into the metencephalon and myelencephalon.
• Different regions of the brain have distinct functions.

Cranial Nerves

• There are 12 pairs of cranial nerves.
• Each nerve has a specific function
• Nerves can have sensory, motor, or both functions
• Cranial nerves develop from different parts of the brain

Brain Flexures

• Brain flexures include cephalic, cervical, and pontine flexures
• Flexures reshape and reorient the developing brain
• Flexures affect the eventual position of different brain parts

Ventricular System and Choroid Plexus

• The ventricular system has cavities in the brain.
• The choroid plexus is a vascular structure in the ventricles.
• CSF is produced by the choroid plexus.

Other Important Terms

• Neuroepithelium: Layer of specialized cells that give rise to neurons and glia.
• Neuroblast: Immature neuron precursor cell.
• Myelin: Fatty insulating substance around nerve fibers, speeding up signal transmission.
• Neural tube: Embryonic structure that develops into the central nervous system.
• Nucleus: Cluster of neuron cell bodies.
• Ganglion: Cluster of neuron cell bodies outside the CNS.

Explore the key concepts of nervous system development and structure, focusing on neuroblasts and the roles of signaling proteins like BMP4 and Sonic hedgehog. This quiz also covers the anatomy of the nervous system, including central and peripheral components as illustrated in a diagram. Test your understanding of the intricate mechanisms involved in neural tissue formation.