  Optical and radio afterglows arising from the shocks by relativistic conical
ejecta running into pre-burst massive stellar winds are revisited. Under the
homogeneous thin-shell approximation and a realistic treatment for the lateral
expansion of jets, our results show that a notable break exists in the optical
light curve in most cases we calculated in which the physical parameters are
varied within reasonable ranges. For a relatively tenuous wind which cannot
decelerate the relativistic jet to cause a light curve break within days, the
wind termination shock due to the ram pressure of the surrounding medium occurs
at a small radius, namely, a few times 10^{17} cm. In such a structured wind
environment, the jet will pass through the wind within several hours and run
into the outer uniform dense medium. The resulting optical light curve flattens
with a shallower drop after the jet encounters the uniform medium, and then
declines deeply, triggered by runaway lateral expansion.
