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Ex utero Electroporation and Whole Hemisphere Explants: A Simple Experimental Method for Studies of Early Cortical Development
Published on: April 3, 2013
Diverse modes of axon elaboration in the developing neocortex
Carlos Portera-Cailliau1, Robby M Weimer, Vincenzo De Paola
1Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA. cpcailliau@mednet.ucla.edu
Plos Biology
|July 20, 2005
Summary
Neural circuits form through axonal elaboration in the neocortex. This study reveals distinct growth patterns for thalamocortical (TC) and Cajal-Retzius (CR) axons, highlighting unique developmental programs.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Axonal arbor development is crucial for neural circuit formation.
- Mechanisms of axonal elaboration in the neocortex remain largely unknown.
Purpose of the Study:
- To investigate the in vivo dynamics of axonal growth and pruning in the developing neocortex.
- To compare the structural and dynamic differences between thalamocortical (TC) and Cajal-Retzius (CR) axons.
Main Methods:
- In vivo two-photon time-lapse microscopy was used to image axons in mouse neocortex.
- Imaging spanned the first 3 weeks of postnatal development, capturing axonal elaboration and synaptogenesis.
- Analysis focused on growth, pruning, and structural characteristics of TC and CR axons in Layer 1.
Main Results:
- TC and CR axons exhibited distinct growth patterns and growth cone morphologies.
- TC axons showed rapid, straight growth with bulbous growth cones, while CR axons grew slowly along tortuous paths with large, filopodia-rich growth cones.
- Branch addition occurred interstitially for both axon types; pruning involved retraction or degeneration.
Conclusions:
- Differences in TC and CR axon structure and dynamics suggest distinct intrinsic growth programs.
- These distinct programs are likely adapted for their respective roles as long projection neurons (TC) and local interneurons (CR).
- The balance of growth and retraction finely tunes axonal arbor formation within the neocortex.
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