  We discuss the effects of interlayer hopping and the resulting
$k_z$-dispersion in the cuprates within the framework of the one-band tight
binding (TB) model Hamiltonian. Specific forms of the dispersion relations in
terms of the in-plane hopping parameters $t$, $t'$, $t''$ and $t'''$ and the
effective interlayer hopping $t_z$ in La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) and
Nd$_{2-x}$Ce$_x$CuO$_4$ (NCCO) and the added intracell hopping $t_{bi}$ between
the CuO$_2$ bilayers in Bi$_2$Sr$_2$CaCu$_2$O$_{8}$ (Bi2212) are presented. The
values of the `bare' parameters are obtained via fits with the first principles
LDA-based band structures in LSCO, NCCO and Bi2212. The corresponding `dressed'
parameter sets which account for correlation effects beyond the LDA are derived
by fitting experimental FS maps and dispersions near the Fermi energy in
optimally doped and overdoped systems. The interlayer couplings $t_z$ and
$t_{bi}$ are found generally to be a substantial fraction of the in-plane
hopping $t$, although the value of $t_z$ in NCCO is anomalously small,
reflecting absence of apical O atoms in the crystal structure. Our results
provide some insight into the issues of the determination of doping from
experimental FS maps in Bi2212, the role of intercell coupling in c-axis
transport, and the possible correlations between the doping dependencies of the
binding energies of the Van Hove singularities (VHSs) and various prominent
features observed in the angle-resolved photoemission (ARPES) and tunneling
spectra of the cuprates.
