The ovary of Xiphinema theresiae is studied ultrastructurally. It consists of two cell types, the ovarian epithelial cells and the germ cells. The ovarian epithelial cells form a thin layer around the germ cells. Their nuclei are located in between the germ cells. At some sites, processes of the ovarian epithelial cells migrate inward and form a central cytoplasmic mass. The germ cells have a large lobated nucleus, with an eccentric nucleolus, and are considered to represent young previtellogenic oocytes. In contact with the central cytoplasmic mass, the germ cells develop two membrane derived features, the villi and the small coated bulges, which most probably play a role in transport.