Axon Growth and Guidance

Question 1

Where is the growth cone, what is its function and how is it adapted to its function?

Answer 1

• The leading edge of the growing axon that responds to growth signals
• Stimulates intracellular signalling which leads to cytoskeletal rearrangements and changes in gene transcription causing axon growth / regeneration
• Adaptation: Highly enriched in receptors that respond to extracellular / molecular cues

Question 2

How can the growth cone respond morphologically upon completion of the intracellular signals in response to the cues it receives?

Answer 2

• Changing direction
• Stalling
• Collapsing
• Forming a pre-synaptic terminal
• Spreading / growing faster

Question 3

Intracellular signalling leads to what mechanistic changes that drive growth cone growth dynamics?

Answer 3

Cytoskeletal changes (actin filaments and microtubules) underlie growth cone dynamics, and hence control axon growth

G-actin and F-actin depolymerisation and polymerisation constitute the actin filament growth mechanics

Question 4

Label the lamellipodia / filopodia…