Abstract
The principal aim of the work described in this thesis was to investigate the toxicological consequences of administering oestrogens in high doses to different mammalian species. Attempts were made to determine whether the toxic effects were attributable to disturbances in endocrine homeostasis or to an unrelated mechanism. Two structurally similar oestrogens (diethylstilboestrol and hexoestrol) were compared at oestrogenically equivalent doses in two contrasting species, the ferret and the rat. The former is a monoestrous carnivore, a seasonal breeder and an induced ovulator. The latter is a polyoestrous rodent, a non-seasonal breeder and a spontaneous ovulator. A subsidiary aim of this work was to evaluate the ferret as a non-rodent alternative to the dog in toxicity studies.