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Abstract

The development and regression of deciduosarcomas and other lesions caused by estrogens and progestins in rabbits (PDF) (HTML) 
Zook,Bernard C.; Janne,Olli A.; Abraham,Andrew A.; Nash,Harold A.
Toxicologic Pathology 29(4): 411-416
Publication date: 2001

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A series of experiments were conducted to study the histopathologicaleffects of a combination of exogenous estrogens and progestinsin mature rabbits. Estradiol (14-45 µ g/day) andlevonorgestrel (30-233 µg/day) were administeredby intravaginal or subdermal Silastic devices for various timeintervals to study the development of lesions with time andto determine if lesions regressed following withdrawal of thesteroids. The origin of splenic decidual tumors (primary ormetastasis from the uterus) was determined by administeringthe same steroid combination to castrated male rabbits. It wasdetermined that uterine decidualization is present after 7 daysof steroid treatment and that neoplasms of decidual cells mayappear in the uterus after only 30 days of steroid administration.Decidual changes were observed frequently in uterine arteries,often concurrent with infarct-like areas of necrosis of theuterine wall. Withdrawal of contraceptive steroids for 14-120days after 60 days' administration resulted in atrophy and disappearanceof decidual cells and decidual tumors. Decidual neoplasms developedin the spleen of all castrated male rabbits given subdermalsteroids, demonstrating that these tumors can arise as primaryneoplasms of the spleen. The foregoing lesions appear to bepeculiar to the rabbit and, together with previous data, suggestthe rabbit to be a poor model for evaluating the effects ofcontraceptive steroids in other species.

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