sentences:  Ultimately, like in the PNS, the longitudinal pathways formed in about 80% of observed segments.Thus, it was shown that the pioneer axons played a role in the development of the CNS and PNS, and without the pioneer axons, the growth of the followers was delayed.Remarkably, the majority of the tracts formed, indicating that other factors play a role in axon guidance that can correct for the loss of pioneer neurons.