  Assume $AD+V=L(\mathbb{R})$. Let $\kappa=\utilde{\delta}^2_1$, the supremum
of all $\utilde{\Delta}^2_1$ prewellorderings. We prove that extenders on the
sequence of $\H$ that have critical point $\kappa$ are generated by countably
complete measures. This provides a partial reversal of Woodin's result that the
$<\Theta$-strongness of $\kappa$ in $\H$ is witnessed by $\kappa$-complete
ultrafilters on $\k$. The aforementioned characterization of extenders works in
a more general setting for all cutpoint measurable cardinals of $\H$ in all
models of determinacy where the fine structural analysis of $\H$ has been
carried out. For example, it holds in the minimal model of the Largest Suslin
Axiom. It also gives a simple proof of a theorem of Steel that the successor
members of the Solovay sequence are cutpoints in $\H$ (in models where $\H$
analysis is carried out).
