Experimental testicular germ cell tumorigenesis in mouse strains with and without spontaneous tumours differs from development of germ cell tumours of the adult human testis.

The aim of this study was to undertake a morphological analysis of the earliest stages of experimentally induced (by genital ridge grafting) germ cell tumours in mouse strains with (129/Sv-ter) and without (MA) spontaneous tumorigenesis. Genital ridges from fetuses aged 12 or 13 days from 129/Sv-ter and MA were transplanted into the testes of adult 129/Sv-ter. The results show clearly that experimentally induced carcinoma-in-situ in mouse testes differs considerably from its human counterpart, found in patients with and without testicular germ cell tumours, and considered to be the precursor for all kinds of germ cell tumours of the adult testis apart from spermatocytic seminoma. The results indicate that development of testicular germ cell tumours is different in man and the mouse.