A New Inbred Subline of Mice (129/terSv) with a High Incidence of Spontaneous Congenital Testicular Teratomas2

Abstract

About 30% of the males of a new inbred subline of mice, 129/terSv, developed spontaneous congenital testicular teratomas. This subline is closely related to strain 129/Sv, and the high incidence of teratomas was probably due to a single gene mutation. Hybrids of 129/terSv and other 129 sublines, presumably heterozygous at this locus, showed an intermediate incidence. Histologically the teratomas in 129/terSv mice were like those in strain 129/Sv. They contained many types of normal appearing immature and adult tissues derived from undifferentiated embryonic stem cells. They rarely metastasized. There was no maternal influence on the incidence of teratomas. Teratomas were experimentally induced in 129/terSv mice by grafting 11-, 12-, or 13-day fetal genital ridges to the testes of adults. The male genital ridges developed into testes, and most had teratomas. The primordial germ cells in 14-day and older genital ridges were resistant to the teratocarcinogenic process. The earliest spontaneous teratomas were observed in the testes of 16-day fetuses, and were composed of small clusters of embryonic cells within the seminiferous tubules. The number of countable foci ranged from 1–17. Grafts of female genital ridges developed into ovaries without teratomas.