  Quark matter is expected to exist in the interior of compact stellar objects
as neutron stars or even the more exotic strange stars, based on the
Bodmer-Witten conjecture. Bare strange quark stars and (normal) strange
quark-matter stars, those possessing a baryon (electron-supported) crust, are
hypothesized as good candidates to explain the properties of a set of peculiar
stellar sources as the enigmatic X-ray source RX J1856.5-3754, some pulsars as
PSR B1828-11 and PSR B1642-03, and the anomalous X-ray pulsars and soft
gamma-ray repeaters. In the MIT bag model, quarks are treated as a degenerate
Fermi gas confined to a region of space having a vacuum energy density
$B_{bag}$ (the Bag constant). In this note, we modif{}y the MIT Bag Model by
including the electromagnetic interaction. We also show that this version of
the MIT model implies the anisotropy of the Bag pressure due to the presence of
the magnetic field. The equations of state of degenerate quarks gases are
studied in the presence of ultra strong magnetic fields. The behavior of a
system made-up of quarks having (or not) anomalous magnetic moment is reviewed.
A structural instability is found, which is related to the anisotropic nature
of the pressures in this highly magnetized matter. The conditions for the
collapse of this system are obtained and compared to a previous model of
neutron stars build-up on a neutron gas having anomalous magnetic moment.
