  Calculations have been performed for the $^{16}$O($\gamma$,pn) and the
$^{16}$O($\gamma$,pp) reaction in the photon-energy range $E_{\gamma}$ = 60-300
MeV. Besides the contribution from the more common photoabsorption on the
pionic degrees of freedom, we have investigated the influence of heavier meson
exchange ($\rho, \sigma, \omega$) and intermediate $\Delta$ creation with $\pi$
and $\rho$ exchange. Whereas the $\pi$ meson is found to set the main trends,
the $\rho$ meson is found not to be discardable in a theoretical description of
the ($\gamma$,pn) reaction. The incorporation of an energy dependence and a
decay width in the $\Delta$ propagator is observed to be essential in order to
arrive at a more realistic description of ($\gamma$,NN) reactions at higher
photon energies.
