  We present a discussion of the effects induced by bulk viscosity either on
the very early Universe stability and on the dynamics associated to the extreme
gravitational collapse of a gas cloud. In both cases the viscosity coefficient
is related to the energy density $\rho$ via a power-law of the form
$\zeta=\zeta_0 \rho^s$ (where $\zeta_0, s=const.$) and the behavior of the
density contrast in analyzed.
  In the first case, matter filling the isotropic and homogeneous background is
described by an ultra-relativistic equation of state. The analytic expression
of the density contrast shows that its growth is suppressed forward in time as
soon as $\zeta_0$ overcomes a critical value. On the other hand, in such a
regime, the asymptotic approach to the initial singularity admits an unstable
collapsing picture.
  In the second case, we investigate the top-down fragmentation process of an
uniform and spherically symmetric gas cloud within the framework of a Newtonian
approach, including the negative pressure contribution associated to the bulk
viscous phenomenology. In the extreme regime toward the singularity, we show
that the density contrast associated to an adiabatic-like behavior of the gas
(which is identified by a particular range of the politropic index) acquire,
for sufficiently large viscous contributions, a vanishing behavior which
prevents the formation of sub-structures. Such a feature is not present in the
isothermal-like collapse. We also emphasize that in the adiabatic-like case
bulk viscosity is also responsible for the appearance of a threshold scale
(equivalent to a Jeans length) beyond which perturbations begin to increase.
