Date of Award


Document Type

Restricted Thesis

Terms of Use

© 2014 Hannah A. Grunwald. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts


Biology Department

First Advisor

Elizabeth Ann Vallen


Motoneuron axons extend during development and are guided to reach very specific synaptic targets. A possible candidate for signaling this outgrowth is the family of heparan sulfate proteoglycans (HSPGs), which are glycosylated proteins embedded in the extracellular matrix. To better understand the role of HSPGs in axon outgrowth and pathfinding we examined motoneuron development and regeneration in two mutants, boxer and dackel which are defective in production of glycosyltransferases responsible for the addition of sugar side chains to HSPGs. dackel mutants frequently failed to extend ventrally-projecting axons, whereas boxer mutants had normal outgrowth levels, but had guidance defects in dorsally-projecting axons. We conclude that normally glycosylated HSPGs are necessary for motor axon outgrowth and guidance during development.