  This paper is a continuation and development of our previous articles (Popov
et al., 1997, 1998). We use `Scenario Machine'' (Lipunov et al., 1996b) -- the
population synthesis simulator (for single binary systems calculations the
program is available in WWW: http://xray.sai.msu.ru/ (Nazin et al., 1998)) --
to calculate evolution of populations of several types of X-ray sources during
the first 20 Myrs after a starformation burst.
  We examined the evolution of 12 types of X-ray sources in close binary
systems (both with neutron stars and with black holes) for different parameters
of the IMF -- slopes: $\alpha=1$, $\alpha=1.35$ and $\alpha=2.35$ and upper
mass limits, $M_{up}$: 120 $M_{\odot}$, 60 $M_{\odot}$ and 40 $M_{\odot}$.
Results, especially for sources with black holes, are very sensitive to
variations of the IMF, and it should be taken into account when fitting
parameters of starformation bursts.
  Results are applied to several regions of recent starformation in different
galaxies: Tol 89, NGC 5253, NGC 3125, He 2-10, NGC 3049. Using known ages and
total masses of starformation bursts (Shaerer at al., 1998) we calculate
expected numbers of X-ray sources in close binaries for different parameters of
the IMF. Usually, X-ray transient sources consisting of a neutron star and a
main sequence star are most abundant, but for very small ages of bursts (less
than $\approx 4$ Myrs) sources with black holes can become more abundant.

Astrophysics