  In this work, we consider the regularity property of stochastic convolutions
for a class of abstract linear stochastic retarded functional differential
equations with unbounded operator coefficients. We first establish some useful
estimates on fundamental solutions which are time delay versions of those on
$C_0$-semigroups. To this end, we develop a scheme of constructing the
resolvent operators for the integrodifferential equations of Volterra type
since the equation under investigation is of this type in each subinterval
describing the segment of its solution. Then we apply these estimates to
stochastic convolutions of our equations to obtain the desired regularity
property.
