This study will evaluate the expression of arginine vasopressin (AVP) by peptide and mRNA quantitation and also measurement of its V1 receptor mRNA, in the arteries and veins of ovarian malignant (cancerous) or benign (non-cancerous) tissue. The investigators will examine whether AVP protein and AVP and V1 receptor mRNA expression vary with respect to tumor histology, intratumoral vascularization and systemic blood pressure.