An ovarian teratoma in a guinea pig.

An ovarian teratoma was diagnosed in a one-year-old, virgin female, Strain 13 guinea pig that died unexpectedly. The left ovary was replaced by a 5.5 x 5 x 3 cm mass. Microscopically, dense fibrous connective tissue, immature neuroepithelium, central and peripheral nervous tissue, respiratory epithelium and cartilage were observed. A similar mass, 1.2 x 1 x 1 cm, composed largely of embryonal neural tissue, was adhered to the abdominal side of the diaphragm. The latter mass probably resulted from transcoelomic seeding by the ovarian tumor.