<prompt> Which one of the following is NOT an epithelial tumour of the ovary: September 2012Serous cystadenomaBrenner tumourClear cell tumourEndodermal sinus tumour  <response>: Ans. D i.e. Endodermal sinus tumour Endodermal sinus yolk sac tumour is a rare tumour but the second most common of germ cell origin 