  We examined correlations between young radio pulsars (PSRs), Supernova
remnants (SNRs) which have different surface brightness values and young star
formation regions (SFRs). Angular correlation of PSRs with SFRs is reliable up
to 4 kpc and considerably strong up to 3 kpc from the Sun. On average this
correlation is stronger for Galactic anticenter directions compared to Galactic
central directions. Angular correlation of SNRs with SFRs is weaker and depends
on the surface brightness of the SNR. Spatial correlation of PSRs with SFRs is
also stronger than spatial correlation of SNRs with SFRs. Dim SNRs show weak
spatial correlation with SFRs. These investigations and analysis of various
data show that the lower limit for masses of progenitors of PSRs is about 9
M$_{\odot}$ and of SNRs (or supernovae) is about 7 M$_{\odot}$.
