Abstract
The mode of inheritance of hydronephrosis was investigated by crossing inbred DDD mice having a high incidence of hydronephrosis and C57BL/6 mice having normal kidneys. In the males, incidences of hydronephrosis in F1 animals were intermediate between the two parental strains at a rate of 32·6% in (DDD × C57BL/6)F1 and 23·4% in reciprocal F1. The same tendency was observed in F2 male animals. In BCF1 males, the number of affected mice was higher in (C57BL/6 × DDD) F1 × DDD (72·4%) than in (DDD × C57BL/6)F1 × C57BL/6 (11·1%). A few affected mice were found among the females of hybrids F1, F2 and BCF1. These results suggested that hydronephrosis in the DOD strain of mice was controlled by polygenes, and that male hormones may have some effect on the occurrence of hydronephrosis.