Development of the nervous system

Development of the nervous system

1. Ectoderm

   • 18 days post gestation: thickens to form neural plate
     • Plate folds to make groove
       • 21st day: Groove closes to form neural tube
         • Neural tube makes CNS
           • 3-4 weeks: three primary vesicles Prosencephalon, mesencephalon, rhombencephalon = tissue around them
             • 5 weeks
               • 5 secondary vesicles: telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
                 • Diencephalon forms eye cup, thalamus, hypothalamus
                 • Development of cerebral cortex
                   • Stem cells line inside of neural tube
                     • First cells make deepest layer
                     • Other layers formed by migrating through existing layers
             • Bit at the end of these forms spinal cord
         • Neural crest migrates to form
           • dorsal root ganglia
           • Enteric plexi
           • Chromaffin cells of medulla
           • Melanocytes of skin
         • Failure = spina bifida
           • Occulta
             • Mildest: 1/2 vertebrae, may be unaware
           • Meningocele
             • Meninges protrude out through spine
             • Spinal cord normal
             • Surgery can remove membranes without spinal cord damage
           • Myelomeningocele
             • Several vertebrae
             • Spinal cord and meninges protrude out the back
           • Symptoms
             • Movement
               • Weakness/paralysis of lower limbs
               • Deformed/dislocated bones
             • Bladder/bowel
               • Urinary incontinence
               • UTI
               • Kidney problems
               • Bowel incontinence
             • Associated hydrocephalus
               • Short attention span
               • Difficulty
                 • Solving problems
                 • Reading
                 • Understanding some spoken language
                 • Planning
           • Risk factors
             • Race: white
             • Meds like anti-seizure
             • Mother
               • Folate deficiency
               • Obesity
               • Uncontrolled diabetes
             • Sex: female
         • Separates from the layer above (epidermis)