Nonsuperconducting metallic single crystals from the n-type high-Tc system Pr2-xCexCuO4 exhibit a 2-dimensional weak-localization behavior at low temps. The authors use the neg. magnetoresistance from the coherent backscattering of electrons in the CuO2 planes as a probe for the microscopic current paths, when the macroscopic current direction is along the c-axis. The anisotropy of the magnetoresistance for the magnetic field parallel and perpendicular to the CuO2 planes provides clear evidence that the voltage drop develops mainly in the (ab) planes. Hence metallic bridging defects between the CuO2 layers are of dominant importance for the c-axis cond. The peculiar anisotropy of rc(T, H) at the superconducting transition of Bi(2212) crystals can be explained following the same lines.