Thursday, January 23, 2014

Axon Guidance part 1

1History¶

• growth cone moves in an ordered and directed manner - Ramon Cajal
• Roger Sperry: Novel prize, experiments in neural pathways in amphibians
  • retinotectal pathway regenerate after being transect: chemoaffinity theory
    • eye rotation results in 180 change in visual field
    • visual map not determined by experience

2Retinotectal pathway¶

• retinotectal pathway: ganglian cells from retina exit via optic nerve, cross at optic chiams, go to super collicus nuclei (tectum)
• chemical cues exist at many points along the way to guide axon
• use dye to retina and time lapse video microscopy to see the pathway
• neuroepithelium rotation : results in the axon grows toward the part of graft
• nasal/anterior cross and go to caudal of tectum
• temperal go to rostral of ipsolateral tectum

3Growth cone¶

• enlargement at the end of growing axon
• has filopodia (finger-like projection) and lamellipodia (sheet-like projections)
• contain microtubules, mitochondira, vesicels, and sites of actin polymerization
• site of new membrane addition
• actin polymer is linked to adhesion molecules on the plasma membrane

• actin retrograde flow allow microtubule to grow and the growth cone advances

• stuff in this lecture is quite basic, just make sure you know how growth cone works