Different members of the semaphorin family of secreted and transmembrane gu
idance molecules play important and diverse roles during neuronal developme
nt. Within the developing grasshopper limb bud, two semaphorins are express
ed in relatively non-overlapping and distinct expression patterns. The esta
blishment of the tibial sensory projection within the limb bud relies on th
e combinatorial action of both semaphorins. In this review, we describe the
function of the two semaphorins in axonal guidance and propose that a hier
archy of cues guide sensory neurons in the developing peripheral nervous sy
stem.