Iron, nickel and cobalt were selected as catalysts for the generation of nanocarbons in the present study. Structural peculiarities: shape, orientation, defects of catalyst particles and fillings of as-prepared specimens were studied using HRTEM analysis. It was shown that orientations of metal particles, located inside carbon nanotubes (nanofibers), along the longitudinal axis for fcc and bee crystal lattices can be characterized by the same directions: [100], [110], [III] and [112]. It was found that fcc-particles of all three metals often contain twins. The obtained results are discussed in the framework of the epitaxial growth model and deformation processes inside nanotubes.