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PT 603 - CNS Development
Fichas del conjunto (33)
- 1Layers of embryonic disc1. Endoderm
2. Mesoderm
3. Ectoderm - 2Neural plate forming- Around 18 days
- Ectoderm thickens along mid-line - 3Neural fold- Neural plate elongates
- Lateral edges fold outward - 4Which disc comes from CNS?Ectoderm
- 5Can neural cells regenerate?No, they are too specialized (generally)
- 6When and where to neurons start to diminishAfter ~ 20
Especially from cerebral cortex - 7Weight of brain decreases?~10% from age 20-90
- NCV also decreases ~10% - 8Rostral end of neural plateEnlarges & becomes brain
- 9Neural folds meet in midline &Form neural tube, which progresses cephalically & caudally
- 10Neural crest develops into1. Sensory, autonomic, & entric gangia
2. Pia/arachnoid
3. Eye sclera
4. Neurolemma
5. Adrenal meduallary cells (cortex)
6. Carotid body receptors - 11Mesoderm develops into?1. CNS vasculature
2. CNS meninges - 12Monocytes become?Microglia
(macrophages in periphery) - 13Layers of neural tube1. Ventricular zone
2. Subventricular zone
3. Intermediate (mantle) zone
4. Marginal zone - 14Ventricular zone- Most central
- Dividing cells here; move out to next 2 layers as precurser cells
- Remaining cells = ependymal - 15Subventricular zone- Layer of small proliferative cells (primitive neuroblasts) can migrate
- Spongioblasts become astrocytes & oligodendrocytes - 16Mantle zone- Neurons that migrate here become grey matter of CNS
- 17Marginal zone- Few cells
- Distant axons migrate in w/ microglia to form pia matter - 18Intrinsic influences- Mostly Genetics
- From within neuron - 19Extrinsic influences- Mainly environmental
- Outside of cell - 20Neural specificty- Predictability of form & connections of neuron (therefore its function)
- Probs genetically determined (migration destination, structural characteristics, physiologic cell properties) - 21Neural plasticity- Variation from predicable pattern
- Probs result of environmental factors (as new synapses & interconnections are established) - 22What is neural plasticity important for?- Rehabilitation
- Understanding primitive reflexes
- Continual processes - 23Modification of intermediate & marginal zone- Intermediate becomes inner gray matter
- Marginal becomes outer white matter - 24IZ cells dorsal to sulcus limitans- Alar plate (mostly sensory function)
- 25IZ cells ventral to sulcus limitans- Basal plate (mostly efferent motor)
- 26By 3rd month of fetal age- spinal cord extends entire length of vertebral column
(later cord doesn't elongate more; but vertebral column does, therefore spinal nerves must elongate and angle caudally to reach intervertebral foramina.) - 27At birth where is caudal end of spinal cord?L3
- 28Where is spinal cord end at teenage?L1-L2
- 29Each pair of spinal nerves associated withA pair of somites (MSK precursors)
- 303rd week, rostral neural tube enlarges into 3 dilations1. Prosensephalon - becomes forebrain
2. Mesencephalon - midbrain
3. Rhombencephalon - hindbrain - 312nd month; 5 vesicles1.
- 32By 4 monthsFissures begin to develop; 1st = lateral cerebral fissure & posterolateral sulcus of cerebellum
- 33Physiologic/functional maturation of nervous system depends on...Progressive myelination
(esp between 3rd trimester & ~ 2 years old)