In these species, unlike mammals, axons of central neurons are able to regenerate. Sperry found that, when he cut the optic nerve of a newt or a frog it grew back and re-established the right connections, so that the animal was able to see normally. So, if there was a fly above its head, the frog struck downward. The simplest interpretation of this was that fibers had grown back from the inverted retina and contacted their original targets. So that implies that growing neurons show specificity in innervating their targets they didn't just connect with the nearest part of the brain, but they connected with those cells that they were supposed to connect to.
Axons actively navigate to their targets by reading chemical cues in their environments.
The tips of growing axons expand to form a specialized structure known as the growth cone . And the growth cones have these long fingerlike projections called filopodia that adhere very strongly to the surface they're passing over. And they exert tension on the rest of the axon, which follows along wherever the filopodia of the growth cone leads. So, when the growth cone reaches a place where it needs to make a decision about which way to turn, it actually seems to hesitate as the filopodia appear to reach out and check out the surrounding environment. And then they turn one way or the other, and the rest of the axon follows along behind.