Development Of Nervous System Flashcards
Development of CNS : germ layers - endoderm
GI tract ,liver and lungs
Development of CNS - mesoderm
Urogenital system , CV system , muscles , bone
Development of CNS : ectoderm (surface ectoderm )
Anterior pituitary ,lens ,cornea
Development of CNS : ectoderm (neural tube )
Posterior pituitary,retina ,optic nerve ,brain ,spinal cord (CNS)
What happens in the 3rd week of development
Notochord induces the cells of the overlying ectoderm to differentiate into neuroectoderm
What does the neuroectoderm contain
Neural plate and neural groove (neural tune develops and neural crest cells migrate )
Development of CNS : ectoderm (neural crest )
Develops into PNS AND ANS
adrenal medulla , autonomic and sensory nerves
What’s happening In neurulation
By the end of week 3
Wide cranial portion - future Brain
Narrow caudal portion - future spinal cord
How does the future spinal cord lengthen
Somites continue to develop and be added to the trunk region
Day 22 of neurulation
Neural folds begin to fuse closing the neural groove
Neuroectodermal cells along crest of folds separate
What happens after day 22 of neurulation
A narrow neural canal is present and it gets smaller as the cells In the wall of the neural tube proliferate
What are the openings in the tube that eventually close and when do they close
Rostral neuropore - closes day 25
Caudal neuropore - closes day 27
What are the primary brain vesicles
Prosencephalon - forebrain
Mesencephalon - midbrain
Rhombencephalon - hindbrain
Secondary blood vesicles
Telencephalon Diencephalon Mesencephalon Metencephalon Myelencephalon
What initially lines the neural tube
A thick layer of neuroepithelium which forms the ventricular zone
What happens in the spinal cord development
Cells in the ventricular zone multiply and they ,ingrate to the intermediate zone (mantle layer)
These cells then different every into neuroblasts which will firm neurons
Where will you find the intermediate zone (mantle layer )
Between the ventricular zone and the marginal zone
What separates the alar and basal plates
The sulcus limitians
The intermediate zone thickens in which 4 regions
Pair of alar plates dorsal horns and dorsal gray columns
Pair of basal plates centrally (ventral somatic motor and lateral horns )
In spinal cord development what forms the gray matter
The intermediate layer
In spinal cord development what forms the white matter
The marginal layer
In spinal development what forms the central canal
The cavity of the neural tube
What does the ventricular zone in spinal development form
The ependymal lining of the central canal
Adjacent mesenchyme condenses to form a primordial menix with two layers : what are the two layers
Inner - derived from neural crests - pia and arachnoid mater
Outer - derived from mesoderm - dura mater
Sclertome - caudal dense part forms ;
The intervertebral disc , forms the anulus fibrous of the disc
How does a hemi vertrbra occur
If one of the pairs of the sclerotomes fail to develop
Which cells of the sclerotome make up the vertebral body
The cranially placed loosely packed cells
What do the remnants of the sclerotome form
They form the mesenchymal primordium of the vertebra
What are the 3 ossification centers
1 centrum - body and 2 neural arch centers (first to ossify )
When does the first primary ossification center appear
By the end of the 7th week
Spina bifida -occulta
No bulge over bony defect
No neurological deficits
Tuft of hair or skin dimple may be present
Spina bifida - cystica meningocele
Bulge over defect
Contains meninges and CSF and subarachnoid space
Spina bifida - cystica with meningomyelocele
Bulge is seen over defect
Contains meninges ,cord and nerves
Spina bifida - cystica with myeloschisis
Skin and bony defect with open spinal cord ,seen as a mass of neural tissue
Meroencephaly
Failure of rostral neuropore to close
Absence of large part of brain and skull
Fatal
Hirschsprung’s disease
Enflamed sigmoid colon
