Getting axons going

摘要

Neurons extend one long axon, through which they transmit electrical impulses to other cells in the nervous system. Surprisingly, it seems that where the axon forms is determined entirely within the neuron. Neurons act as electrical relays: they collect information from other neurons through multiple extensions called dendrites, and transmit this information through one long protrusion, the axon. But the mechanism that determines where the axon forms at the neuronal surface has been unclear — it might be determined by an extracellular cue or by some intrinsic polarity that exists in the neuron even before the axon begins to grow. On page 704 of this issue, Calderon de Anda et al. resolve this question by describing an unexpected correlation between axon outgrowth and the position of the centrosome — a structure that is involved in organizing the cell's internal scaffolding. The authors propose that where the axon forms is ultimately determined by the orientation of the neurons final cell division, after which it becomes fully specialized.