The evolution of the domain structure during polarization reversal has been investigated in plates of lithium niobate with spatially inhomogeneous electrical conductivity produced by vacuum annealing. The formation of charged domain walls in the crystal bulk has been studied. Revealed features of the domain growth in the bulk have been attributed to the formation of nanodomains under the pyroelectric field and inhomogeneous spatial distribution of the electric field. Creation of the charged domain walls with controlled parameters is of great interest for domain walls engineering.