Summary

Hereditary hydronephrosis was detected in all of the male mice of DDD inbred strain maintained at the National Institute of Animal Health Japan, but in only a few of the females. From the standpoint that male hormones are related to the development of hydronephrosis in this strain, the incidence and severity of the disease were investigated in gonadecto-mized mice treated with testosterone. In the males, the incidence of hydronephrosis-was 50 % (7/]4) in the control (gonadectomized) group, and 73'3% (11/15), 100 % (13/13) and]00 % (12/12) in the 0,] mg, 3·3 mg and 10mg treatment groups respectively. The same tendency was observed in the female animals, though the incidence in each group was not so high. In both sexes the degree of severity increased in proportion to the dose of testosterone adminis-trated. Blood testosterone levels were higher in intact DDD mice than in CS7BL/6 mice, which had normal kidneys in both sexes. These results suggest that male hormones playa significant role in the development of hydronephrosis. In mice of the inbred strain DOD maintained at the National Institute of Animal Health (Japan), spontaneous heritable hydronephrosis was found at a rate of 100 % in the males, but in only a few of the females. Severity of the disease was also greater in the males than in.the females (Nakajima, Imamura