  Some useful developments in the model physics are briefly presented, followed
by model results on chemical enrichments and WR stars. We discuss the expected
rotation velocities of WR stars. We emphasize that the (C+O)/He ratio is a
better chemical indicator of evolution for WC stars than the C/He ratios. With
or without rotation, at a given luminosity the (C+O)/He ratios should be higher
in regions of lower metallicity Z. Also, for a given (C+O)/He ratio the WC
stars in lower Z regions have higher luminosities. The WO stars, which are
likely the progenitors of supernovae SNIc and of some GRBs, should
preferentially be found in regions of low Z and be the descendants of very high
initial masses. Finally, we emphasize the physical reasons why massive rotating
low Z stars may also experience heavy mass loss
