Ch.4/Development Stuff Flashcards
What does the Nervous System form from?
Ectoderm - outermost cell layer
Stage 1 of development in the NS
Neurogenesis - division of nonneuronal cells to produce neurons
Stage 2 of development in the NS
Cell migration - movements of nerve cells to establish distinct populations
Stage 3 of development in the NS
Cell differentiation - refining of cells into types of neurons/glial cells through gene expression
Stage 4 of development in the NS
Synaptogenesis - establishment of synaptic connections as axons grow
Stage 5 of development in the NS
Neuronal cell death - selective death of many nerve cells
Stage 6 of development in the NS
Synapse rearrangement - loss of some synapses & development of others, thru lifespan
Forming of the NS
Thickening of ectoderm > neural plate
Neural plate forms Neural groove (dip)
Groove closes & forms neural tube
Tube forms spinal cord & brain
Neural tube defects
Spina Bifida doesn’t close properly, so spinal cord & fluid bud out of body
-Causes: lack of folic acid; alcohol, nicotine
Teratogen
Things that lead to birth defects
When do major divisions of CNS develop
18 days - three layers of cells: endoderm, mesoderm, ectoderm
20 days - neural groove begin - closed @ 22
25 days - 3 major brain divisions, fore, mid, hindbrain
Where does mitosis occur
Ventricular zone
How does environment determine cell type?
o Encountering high Shh – becomes glia
o Encountering med Shh – motor neuron
o Encountering low Shh - interneurons
Synaptogenesis - how influenced by chemicals
Formation of synapses
Cells attracted via chemicals & forms synapse
NGF - promotes axon survival
Neurotrophins
Family of proteins essential for development of vertebrate NS
