  We present the analysis of morphological and photometric properties of a
sample of isolated spirals with (18) and without (11) an active nucleus, based
on near-infrared imaging in the J and K' bands. The aim of this analysis is to
find the differential properties that could be directly connected with the
phenomenon of nuclear activity. We stress the importance of using isolated
objects for that purpose. Our study shows that both sets of galaxies are
similar in their global properties: they define the same Kormendy relation,
their disk components share the same properties, the bulge and disk scale
lengths are correlated in a similar way, bar strengths and lengths are similar
for primary bars. Hosts of isolated Seyfert galaxies have bulge and disk
properties comparable to those of isolated non active spirals. Central colors
(the innermost 200 pc) of active galaxies are redder than the centers of non
active spirals, most probably due to AGN light being re-emitted by the hot dust
and/or due to circumnuclear star formation, through the contribution of
giants/supergiants. Only one of the Seyfert galaxies in our sample does not
present a primary bar,but both primary and secondary bars are equally present
in active and control objects. Secondary central elongations (associated with
secondary bars, lenses, rings or disks) may be somewhat different. Numerical
models indicate that such secondary bars are not strictly necessary to feed the
central engine when a primary bar is present. Our results show that down to
scales of 100-300 pc, there are no obvious differences between active and non
active spiral galaxies.
