Flashcards in Development Of Multicellular Org II Deck (41):
Growth Cones travel towards target cells along what?
Short term effects of NGF
- Effect on growth cone and Neurite extension
- Local, direct, and rapid
- INDEPENDENT of communication with the cell body
How many neurons in the brain?
Phase 2 of Neural Development
- Axons and Dendrites grow out along specific routes
- Setting up a Provisional but ORDERLY Network of connections b/w various parts of the system
Formation of the neural tube
- Starts w/ a Neural GROOVE on the Dorsal side of the Embryo
- Gradually deepens as Neural FOLDS become elevated
- Ultimately the folds meet and coalesce in the middle
- Closes to form a tube
Ex of Chemotactic Factors
1. Netrin (attractant)
2. Slit (repellent)
3. Semaphorin (repellent pushing Neuron to Brain)
Neural crest generate what cell types?
1. Neurons and Glial cells of the PNS
2. Epinephrine producing cells of adrenal gland
3. Many Skeletal and CT of the HEAD
T/F: Axons and Dendrites are NOT distinguishable at first?
Characteristics of Chemotactic Factors
- Secreted by cells
- Acts as guidance factors at strategic points along path
- May be Attractive or Repulsive
Closure of the Neural Tube
Roof Plate of the Neural Tube secretes what?
BMP and Wnt
What does Signal proteins secreted fro the Ventral and Dorsal side of the Neural Tube do?
- Act as opposing Morphogens
- Causing neurons at diff D/V positions to express Different Regulatory proteins
Derived from the Neural CREST
- Nerves, sensory neurons
What triggers the lasting change in synaptic strength?
Entry of Ca2+ through the Glutamate receptor
What regulates which growth cones synapse and where?
Signal from target tissue
The center of the Neural Tube is called what?
Typical axon length range
Less than 1mm
More than 1m
What Matrix molec favors growth? Which one inhibits it?
2. Chondroitin Sulfate PTG
What forms a axon in Neuronal migration?
When a growth CONE starts migrating Fast
- Develops Axon-Specific Proteins
How many connections does one Neuron make?
Neural crest Migration
Migrate extensively during or shortly after neurulation
The Fate of the Neural Crest cells depend on what?
Where the MIGRATE to
What rules are Synaptic Remodeling dependent on?
1. Axons from cells in DIFFERENT regions of Retina COMPETE for tectal neurons
2. Axons from NEIGHBORING sites which are excited at SAME time to strengthen synapses
Role of the Tectum
Responsible for Visual and Auditory Reflexes
Floor Plate of the Neural Tube secretes what?
Where do Neural Crest cells originate?
From the DORSAL End of the Neural Tube
Long term effects of NGF
- Effect on cell Survival
- Mediated by its receptor
- Uptake into cells via Endocytosis and stimulation do downstream signaling pathways
Derived from the Neural TUBE
- Brain, SC, Retina
Activity Dependent synaptic remodeling is dependent on what?
Why do 50% of Neurons die after they reach target cell?
- Made in excess
- Target cell produces limited amount of specific Neurotropic factors needed for survival
- Those that do not get enough die by PCD
Phase 1 of Neural Development
- Diff cell types (Neurons, glia) develop INDEPENDENTLY
- At widely separate locations in embryo according to local program
Neurons are produced in association with what?
In the Neural Tube, what controls Lateral Inhibition and Positive Feedback?
EMC mediated by what?
Homophilic Cell adhesion molecules
1. IG Superfamily
2. Cadherin Family
Growth cone behavior
- Dictated by its cytoskeletal Machinery
- Throw out Filopodia and Lamelopodia
What controls the movement of Growth Cones?
- Monomeric GTPases Rho and Rac
- They control the assembly/disassembly of ACTIN Filaments
Characteristics of Nerve Growth Factor.
- Belongs to fam of Neurotrophins
- NGF receptor is Tyrosine Kinase A
- Promotes the SURVIVAL of specific sensory neurons and sympathetic neurons
The two ways that Growth Cones find their way around.
1. ECM Environment
- Sensed by RECEPTORS present on membrane
2. Chemotactic Factors
- Released by Neighboring cells
- Attractive or repulsive
- Spiky enlargement on the tip of the Axon/Dendrite
- Crawls through surrounding tissue
Phase 3 of Neural Development
- Continues in ADULT life
- Connections are adjusted and refined through interactions
- Distant regions are connected via electric signal