My lab studies the cellular and molecular mechanisms underlying sexual differentiation of vasopressin synthesis and release. We also study the functional significance of sex differences in this exquisitely hormone-sensitive system, focusing on its role in parental behavior. Our approach is multidisciplinary. We have used, for example, neuronal tract-tracing, immunocytochemistry, in-situ hybridization, neural transplants, injections of psychopharmaca, and various developmental manipulations to answer these questions. Although most of our studies have been done in rats, we now use mainly mice and voles; mice because they allow us to explore the function of individual genes; voles, because they allow us to test the role of sex difference in neural structure in parental behavior, which is readily displayed by male and female prairie voles.