Parthenogenesis has been suggested to be tightly coupled with developm
ent of ovarian teratomas. Indeed, ovarian tumors developed in c-mos-de
ficient female mice, which are characterized by the parthenogenetic ac
tivation of oocytes. The tumors appeared at a frequency of 30% between
4 and 8 months of age, and did not develop in younger or older mice.
Most of the tumors were benign and consisted of multi-focal cysts most
notably with mature ectodermal components, but also with mesodermal a
nd endodermal components. One among 17 tumors observed consisted of ex
tra-embryonic tissues alone, and two bore malignant components with me
tastasis to peritoneal organs. The results strongly suggest the involv
ement of c-mos mutations in human germ cell tumors.