Lecture Notes: Brain Development and Structure

Overview of Brain Development

• The central nervous system structures originate from the neural tube.
• Neural Tube
  • Tube of cells with a fluid-filled center.
  • Composed of embryological stem cells.
  • Develops into brain and spinal cord.

Primary Brain Vesicles

• Proencephalon becomes the forebrain.
• Mesencephalon becomes the midbrain.
• Rhombencephalon becomes the hindbrain.
• The rest of the tube forms the spinal cord.

Secondary Brain Vesicles

• Proencephalon develops into:
  • Telencephalon
  • Diencephalon (Thalamus, Hypothalamus, Epithalamus, and Retina)
• Mesencephalon remains as the midbrain.
• Rhombencephalon develops into:
  • Metencephalon (Pons and Cerebellum)
  • Myelencephalon (Medulla oblongata)

Brain Structures and Fluid-Filled Spaces

• Adult brain regions:
  • Telencephalon forms cerebral hemispheres and encases the diencephalon.
  • Diencephalon deep within the brain.
  • Brain Stem consists of midbrain, pons, and medulla oblongata.
  • Cerebellum is part of the hindbrain.
  • Spinal Cord is the continuation of the neural tube.
• Ventricles
  • Lateral Ventricles in cerebral hemispheres.
  • Third Ventricle surrounded by diencephalon.
  • Cerebral Aqueduct in the midbrain.
  • Fourth Ventricle with pons, cerebellum, and medulla oblongata.
  • Central Canal in the spinal cord.

3D Developmental Perspective

• The neural tube folds, differentiating into vesicles:
  • Telencephalon forms the majority (cerebral hemispheres).
  • Diencephalon, Mesencephalon, Metencephalon, Myelencephalon
• Adult brain differentiation:
  • Telencephalon overgrows, forming infoldings (cortical surface).

Brain Tissue and Composition

• Gray Matter
  • Composed of non-myelinated neurons and cell bodies.
  • Contains many organelles and proteins, giving a gray appearance.
• White Matter
  • Composed of myelinated axons.
  • Myelin is lipid-rich, appearing lighter.

Ventricular System

• Fluid-filled chambers are interconnected, filled with cerebrospinal fluid (CSF).
• Lateral Ventricles are C-shaped in each hemisphere.
• Third Ventricle connects to lateral ventricles via Interventricular Foramen (Monro).
• Fourth Ventricle connects via Cerebral Aqueduct.
• Apertures allow CSF to surround the brain for cushioning.
• Septum Pellucidum separates the lateral ventricles.