Disturbances in sexual differentiation of rat foetuses following spironolactone treatment.

Pregnant rats were treated with 40 mg spironolactone (sp) po from the 13th to the 21st day p.c. The foetuses were prepared and histologically examined on day 22. The male foetuses showed distinct signs of feminization especially of the external genitalia. The anogenital distance was nearly 48% shorter than that of the controls. The prostatic utricle persisted more distinctly, and the number and size of the prostatic buds were significantly reduced. The degree of feminization of the male foetuses which is achieved under the influence of sp (40 mg/day) is the same as that which can be induced by 1--3 mg cyproterone acetate.