Lecture 9 Flashcards
(Week 3) Lateral Edges of Neural Plate (in front of primitive node) become?
Neural Folds
Notochord and Paraxial Mesenchyme causes?
Ectoderm to form Neural Plate
(Week 3) Neural Tube?
Forms CNS
(Week 3) Neural Crest?
Forms PNS and ANS
(Week 4) Neural plate forms?
Neural tube and neural crest cells (Neural tube becomes CNS) (Neural crest cells become PNS and ANS)
Cranial 2/3 of neural plate and tube become?
(As far caudal as 4th pair of somite’s)
Future Brain
Caudal 1/3 of neural plate and tube become?
Spinal Cord
Neural Folds fuses opposite of?
4th-6th somite’s forming neural tube (open at both ends (Cranial/Rostral Neuropore: closes ~25 days) (Caudal Neuropore: closes ~27 days)
(Neural Folds) Cranial/Rostral Neuropore closes?
~25 days
(Neural Folds)
Caudal Neuropore closes?
~27 days
(Spinal Cord Development)
Caudal 1/3 of neural plate and tube becomes?
Spinal Cord
(Spinal Cord Development)
Lateral walls of neural tube thicken?
Decreasing neural canal size
(Spinal Cord Development)
Initially, walls of neural tube are composed of?
Thick pseudo stratified columnar neuroepithelium
(Spinal Cord)
Proliferation and differentiation of neuroepithelial produce?
-Thick Walls
-Thin Roof and Floor Plates
(Spinal Cord)
Sulcus Limitans?
-Differential thickening of lateral walls
-Separates alar and basal plate
(Spinal Cord)
Neuroepithelial cells constitute?
-Intermediate (Mantle) Zone
-Ventricular Zone (ependymal cells)
-Marginal Zone
(Spinal Cord)
Intermediate (Mantle) Zone?
-Contains Alar and Basal Plates
-Gray Matter
(Spinal Cord)
Ventricular Zone (ependymal cells)?
(Gives rise to all (in the spinal cord))
-Macroglial Cells
-Neurons
(Spinal Cord)
Marginal Zone?
(Consists of outer parts of neuroepithelial cells)
-Becomes white matter
Neuroepithelial cells in the ventricular zone differentiate into?
Primordial neurons (neuroblasts)
Neuroblasts become?
Neurons as they develop cytoplasmic processes
Alar plate is responsible for ______ neurons and forms _____ horn of spinal cord?
Sensory; Dorsal
(Spinal Nerve Formation)
Cells from Doral Rami –>?
Dorsal Rami –> Spinal Nerve –> Dorsal Root Ganglia –> Dorsal Roots –> Dorsal Horn
(Spinal Nerve Formation)
Cells from Ventral Horn –>?
Cells from Ventral Horn –> Ventral Roots –> Spinal Nerve –> Ventral Rami
(Spinal Nerve and Vertebral Column)
Conus Medullaris (end of spinal cord)?
Ends at:
-Birth: L3
-Adults: L1-L2
(Spinal Nerve and Vertebral Column)
Myelination?
-Schwann Cells: PNS
(Derived from neural crest cells)
-Oligodendrocytes CNS
(Derived from neural tube)
(Neural Tube defects (NTD))
There are multiple sites of closure of neural tube. Failure of closure leads to?
-Spina bifida cystica
-Meroencephaly (anencephaly)
-Craniorachischisis
(Folic Acid Fortification)
(Neural Tube defects (NTD))
Spina Bifida?
(Spina Bifida Occulta (most common))
(Spina Bifida Cystics (meningeal cysts))
-Spina Bifida Meningocele
-Spina Bifida Meningomyelocele (more common and severe than meningocele)
-Spina Bifida Myeloschisis (most severe types)
(Neural Tube defects (NTD))
Spina Bifida Occulta?
(most common)
-Neural arche(s) failed to fuse in median plan (Unfused Arch)
-Most commonly occurs at L5 and S1
-Presents with small dimple and tufted hair (or lipoma, dermal sinus etc.)
(Neural Tube defects (NTD))
(Spina Bifida Cystica (meningeal cysts))
Spina Bifida Meningocele?
-Unfused Arch
-Meninges
(Neural Tube defects (NTD))
(Spina Bifida Cystica (meningeal cysts))
Spina Bifida Meningomyelocele?
(more common and severe than meningocele)
-Unfused Arch
-Meninges
-Spinal Cord
(Neural Tube defects (NTD))
(Spina Bifida Cystica (meningeal cysts))
Spina Bifida Myeloschisis?
(most severe type)
-Spinal Cord is open
-Neural folds failed to close
-Results in permanent paralysis or weakness in lower limbs
(Dermal Sinus)
Birth Defect?
Failure of surface ectoderm to detach from neuroectoderm and meninges that envelop it
(Dermal Sinus)
Meninges become continuous with a narrow channel?
Extends to a dimple on skin in sacral region
(Dermal Sinus)
Dimple indicates?
(Region of closure of caudal neuropore)
-Last place of separation between Surface ectoderm and neural tube
Caudal Neuropore closes roughly at?
End of 4th week
Spinal Cord ends at ____ for newborns and myelination of ganglion surrounding spinal cord are due to cells derived from where?
L3; Neural Crest
(Development of Brain)
Develops in 3rd week when neural plate and tube are developing from?
Neuroectoderm
(Development of Brain)
Neural Tube, cranial to 4th pair of somites, develops into?
Brain
(Development of Brain)
Fusion of neural folds in cranial region and closure of rostral neuropore forms 3 vesicles?
-Forebrain (prosencephalon)
-Midbrain (mesencephalon)
-Hindbrain (rhombencephalon)
(Brain Vesicles and Ventricles)
Wall of neural tube becomes?
Brain
(Brain Vesicles and Ventricles)
Lumen of neural tube becomes?
Brain Ventricles (CSF formed here)
(Brain Vesicles and Ventricles)
Neuroepithelial cells give rise to?
-Macroglial cells
-CNS
Microglia?
-Originate from mesenchymal cells
-Enters CNS via blood vessels
(Pituitary Gland Development)
Neurohypophysial Diverticulum?
-Neuroectodermal down growth from diencephalon
-Forms neurohypophysis
(Pituitary Gland Development)
Hypophysical Diverticulum?
-Ectodermal upgrowth from stomodeum
-Forms adenohypophysis (Rathke’s Pouch)
(Myelencephalon and 4th Ventricle)
Pontine Flexure?
Divides Hindbrain into:
-Metencephalon (Pons) (Cerebellum)
-Myelencephalon (Medulla)
(Flexure causes thinning of roof of 4th ventricle)
(Cranial Nerve Nuclei)
Special Somatic Afferents?
Sense of balance and gravity
(Cranial Nerve Nuclei)
Special Visceral Efferents?
Skeletal muscles of branchial arch origin
(Metencephalon and 4th Ventricle)
Metencephalon?
-Ventral Portion: Pons
-Dorsal Portion: Cerebellum
(Metencephalon and 4th Ventricle)
Roof of 4th Ventricle?
Choroid Plexus:
-CSF flows subarachnoid space via 3 foramina (Foramen of Luschka (2)) (Foramen of Magendie (1))
Mesencephalon?
-Cranial to pontine flexure (thus, no thinning of roof)
-Cranial most extent of sulcus limitans
-Lumen (cerebral aqueduct)
Diencephalon?
(Lateral walls of Diencephalon contain:)
-Thalamus, Hypothalamus and Epithalamus
(All these nuclei are composed of:)
-Derived Alar Lamina Association Cells
(Lumen:)
-3rd Ventricle (Rostral wall is formed by lamina terminals (cranial-most end of original neural tube)
Telencephalon?
(Telencephalon forms:)
-Cerebral Hemispheres
-Lateral Ventricles
(Telencephalon form as:)
-Lateral diverticula of original neural tube
(In cerebral hemispheres:)
-Wall of neural tube things (leading to formation of choroid plexus in floor and medial walls of lateral ventricles/Roof of 3rd ventricle)
Pontine Flexure divides which structure?
This structure also contains which ventricle?
Hindbrain; 4th Ventricle
(Cranium Bifidum)
Cranial Meningocele?
Meninges with CSF
(Cranium Bifidum)
Meningoencephalocele?
-Meninges with CSF
-Portion of Cerebellum
(Cranium Bifidum)
Meningohydroencephalocele?
-Meninges with CSF
-Portion of Occipital Lobe
-Portion of posterior horn of lateral ventricle
(Other Disorders)
Hydrocephalus?
-Imbalance between production and absorption of CSF (leading to excess CSF in ventricles)
-Significant enlargement of head
-Rare cases: Increased production of CSF via choroid plexus adenoma
(Other Disorders)
Meroencephaly?
-Defect of calvaria and brain (failure of rostral neuropore to close at end of 4th week)
-Forebrain, midbrain, most of hindbrain and calvaria are absent
-Exencephaly (brain exposed or extruding from cranium) (nervous tissue degenerates)
(Other Disorders)
Microcephaly?
-Reduction in brain growth (without affecting brain structure)
-Calvaria and brain are small (face is normal size)
