Neuroscience 2001 Abstract
| Presentation Number: | 472.11 |
|---|---|
| Abstract Title: | L1 CONTRIBUTES TO SENSORY AXON GUIDANCE IN THE EMBRYONIC CHICK HINDLIMB. |
| Authors: |
Xue, Q. S.*1
; Camilli, S. J.1
; Honig, M. G.1
1Anatomy and Neurobiology, Univ. of Tennessee, Memphis, TN |
| Primary Theme and Topics |
Development - Axonal and Dendritic Development -- Axon guidance: receptors and signaling mechanisms |
| Secondary Theme and Topics | Development<br />- Axonal and Dendritic Development<br />-- Axon outgrowth: receptors and signaling mechanisms |
| Session: |
472. Axonal and dendritic development: axon guidance--PNS Poster |
| Presentation Time: | Tuesday, November 13, 2001 10:00 AM-11:00 AM |
| Location: | Exhibit Hall B-29 |
| Keywords: | DEVELOPMENT, DORSAL ROOT GANGLION, EMBRYO, NEURITE OUTGROWTH |
The cell adhesion molecule L1 plays an important role in sensory axon pathfinding in the developing chick hindlimb. We have previously shown that when function-blocking anti-L1 antibodies are injected into the limb at St. 25, shortly before most sensory axons enter the plexus, the segmental pattern of sensory projectons is altered. To elucidate how anti-L1 causes pathfinding errors, here we anterogradely labeled small numbers of sensory neurons 5-6 hours after anti-L1 injection and later traced the trajectories of individual axons. We overlaid camera lucida drawings of the plexus with a grid consisting of equally spaced parallel lines, oriented so that it was aligned with the predominant direction of axon growth. We counted how often sensory axons crossed the grid lines and expressed the total number of crossings relative to the number of axons in the region of interest. In anti-L1-injected limbs, the incidence of crossing was nearly twice that of normal embryos. In addition, the frequency of axons turning at angles greater than 30° in anti-L1-injected limbs was almost twice the normal value. Thus, after anti-L1 injection, sensory axons followed trajectories that were less straight and more tortuous than normal. This change presumably results from the decreased axon-axon adhesion that is associated with the blockade of L1 function. Interestingly, the relative increase in the complexity of axonal trajectories is greater than the previously reported increase in projection errors. Taken together, the results suggest that by helping sensory axons grow in tight fascicles, L1 normally limits their ability to wander too widely and thereby serves to facilitate appropriate pathfinding.
Supported by NIH (NS34404 to MGH)
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2001 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2001. Online.
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