Neuroembryology

Neuroembryology

1. Early development of nervous system

   • Formation Neural Plate
     • Mesoderm
       • NOTOCHORD
         • cordomesoderm
         • Source SHH
     • Endoderm
     • Ectoderm
       • Nervous system + skin
         • Day 18- neural plate
           • 19- expand
             • 20-groove
               • Medial neural hinge point (MHP)
                 • Anchor to notochord
               • epidermal cells to center
           • AP/DV patterning
           • Secrete
   • Neurulation and related
     • Tube
       • 23- Tube close
         • 24- Cranial Neuropore close
           • 26- Caudal close
         • dorsolateral hinge point (DLHP)
           • wedge-shape
         • neural crest cells disperse
           • neural tube separate from epidermis
     • Crest
     • Placodes
     • The folding process that transforms neural plate into neural tube/crest
   • Consequences disruption neurulation
     • Ancephaly
       • No brain
     • Spina bifida
       • Weird Ass (maybe just a tuft of hair)

2. Molecules in EARLY neural tube formation

   • Cadherins
     • E-cadherin
       • epithelial
     • N-cadherin
       • Neural
         • separate
     • Crest has none
   • BMP and Wnts
     • Later
       • dorsalize nervous system
         • ventral
           • motor
         • Dorsal
           • Sensory
       • rostro-caudal patterning
         • Anterior (rostral)
           • Wnt/BMP
             • non-hox determine segment
         • Hindbrain
           • FGFs
             • Rhombencephalon
               • somites first
         • Posterior
           • Retinoic acid
             • mesoderm
               • posterior hindbrain segments
                 • Rhombomeres
           • spinal cord
             • segmented nervous system
         • Hox Genes
           • Activated by Cdx
             • Activated by patterning
           • Homeobox genes
             • Homeodomain
               • DNA binding
           • Master genes
             • Gradients
       • dorsal epidermal ectoderm
         • Formation roof plate
           • Source dorsalizing morphogens
             • TGF-B family
     • Early
       • Secreted protein factors
         • Suppress neural induction
           • Neural plate default
         • Gastrula organizer
           • express BMP inhibitors
             • suppress epidermal

3. Neural Crest and neural placodes

   • Crest
     • PNS + ANS ++++
       • Including face!
       • Tumors
         • hair, pigment, bone, teeth, neuron
   • Neural Placodes
     • Embryonic ectoderm
       • Non-neural
         • Epidermis
       • Neural
         • Neural plate
           • CNS
       • Neural border
         • Pre-placodal
           • Lateral line
           • neurons
             • Olfactory
               • olfactory sensory
             • Trigeminal
               • neurons trigeminal ganglion
             • Epibranchial
               • ganglia cranial nerves VII, IX and X
             • Otic
               • otic pit
                 • hearing
               • otic vesicle
                 • equillibrium
                 • relay neurons
           • Non neurons
             • Adenohypohyseal
               • anterior of pituitary gland
             • Lens
               • under direction of optic vesicle
                 • lens of eye
         • Neural crest

4. Neural Tube: CNS organization

   • Thickening neural tube
     • Alar
       • somatosensory information
         • Dorsal horn
         • Brainstem
     • Basal
       • Motor neurons
         • autonomic
         • somatic
   • Sulcus limitans
     • remains, visible groove
       • brainstem

5. Divisions cranial neural tube

   • Prosencephalon (forebrain)
     • Telencephalon
       • Cerebral hemisphere
         • Lateral ventricles
     • Diencephalon
       • (hypo)thalamus, neurohypophysis
         • Most of third ventricle
   • Mesencephalon (midbrain)
     • Midbrain
       • Cerebral aqueduct
       • Mesencephalic flexure
   • Rhombencephalon (hindbrain)
     • Metencephalon
       • Pons, cerebellum
         • Rostral 4th ventricle
         • Pontine Flexure
     • Myelencephalon
       • Medulla
         • Caudal 4th ventricle
         • Cervical Flexure

6. Development of the Brainstem

   • Roofplate
     • choroid plexus
       • Produce CSF
   • Cavity
     • 4th ventricle
       • 2 lateral apertures and one caudal
         • Connect ventricular
           • Subarachnoid space
   • Alar
     • Sensory and association nuclei
     • Pons
       • Dorsolateral lip
         • Cerebellum
           • much of it made postnatally. Weird.
         • Rhombic lip
   • Basal
     • forms cranial nerve and autonomic motor nuclei

7. Development of forebrain

   • Third ventricle
     • Split by hypothalamic sulcus
       • below hypothalamus
       • Above thalamus

8. Disorders cellular migration/development

   • Mostly disorders of migration
   • Seizures
     • Lissencephaly
       • Pachygyria
         • broad, thicker gyri
           • more common
       • Agyria
         • lack gyri
       • cerebellar hypoplasia
         • Reelin mutation
     • Heterotopias
       • Abnormal accumulation cortical neurons
   • Retardation
   • Abnormal connectivity
     • disordered connection
       • Wrong place/ wrong time
     • disordered numbers

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