  Recent studies show the possibility of the formation of fairly regular and
global spiral patterns in dwarf galaxies (dS type). Our sample of observed
dwarf objects of this class also includes galaxies with a central stellar bar.
The analysis of the observational data provides a small rotation velocity and a
small disk component mass for dS galaxies, which is in poor agreement with the
spiral structure generation mechanism in isolated dwarfs due to the development
of disk gravitational instability. Numerical simulation of the stellar-gaseous
disks self-consistent dynamics imposes restrictions on the stellar disk
thickness and the maximum gas rotation velocity, at which the gravitational
mechanism of spiral formation can still be effective.
