Peripheral glia fail to initiate their migration in mutant embryos and accumulate at the central nervous system-peripheral nervous system transition zone. The number of glial cells is increased compared to controls. The mutant embryos show severe axonal patterning defects in the central nervous system, whereas the major axonal tracts are still present in the peripheral nervous system.

rap^8F3 mutant clones show a significant increase in the number of glia compared to adjacent wild-type nervous system.