Axon guidance mechanisms and molecules:: Lessons from invertebrates

Vertebrates and invertebrates share the formidable task of accurately establishing the elaborate connections that make up their nervous systems. Researchers investigating this process have the challenge of identifying the molecules and mechanisms that underlie this process. Each group of organisms offers their own advantages for piecing together the conserved constituents. Broadly speaking, the invertebrates have allowed the discovery of relevant genes through classical genetic screens for mutations that affect the process of axon guidance, whereas vertebrates provide numerous systems for the elaboration of the functional mechanisms. Here, we focus on the role of invertebrates in characterizing the molecular mechanisms of axon guidance.