Strain differences in susceptibility of female mice to 1,2-dimethylhydrazine.

C3H, CBA, C57BL/6j, (CBA x C57BL/6j)F1, BALB/c, DBA/2, C3HA and AKR female mice were treated with 25 weekly s.c. injections of a solution of 1,2-dimethylhydrazine (DMH) in water at a dose level of 8 mg/kg body weight. BALB/c mice appeared to be most sensitive to the induction of epithelial colorectal (93.3%) and anal tumours by DMH. There was, however, a dissociation between the severity of the macroscopical tumour lesions in the colon of BALB/c mice and their relatively weak tendency to infiltrative growth. C3HA mice were more resistant to the induction of intestinal tumours (30.9%) but the tumours showed a deep invasion into the intestinal wall. There was no correlation between the strains and within a given strain between the development of colorectal and anal neoplasms. C3H and CBA mice strains developed a high incidence of uterine sarcomas (37.5 and 40.7%, respectively) which were not found at all in BALB/c, DBA/2 and C3HA mice and which appeared in C57BL/6j and AKR mice at low frequency (2.7 and 7.7%, respectively). C57BL/6j, BALB/c, DBA/2 and C3HA mice developed haemorrhagic lesions of the ovaries (35.1, 46.7, 62.9 and 85.7%, respectively). These lesions, which led to peritoneal haemorrhage, were one of the main causes of death in C3HA and DBA/2 strains. It seems that, with the exception of AKR mice, an inverse relationship exists between the occurrence of haemorrhagic ovarian lesions and development of uterine sarcomas in female mice treated with DMH.