Spontaneously Occurring Fibroid Tumors of the Laying Hen Oviduct

Abstract

Spontaneously occurring benign uterine leiomyomas (fibroids) are the most common reproductive tract tumor of women in the United States. It is estimated that more than 70% of women will develop uterine fibroids and the presence of these tumors is a primary reason for hysterectomies. Research into the causes and treatment of uterine fibroids is hampered by a lack of reliable animal models for the disease. Leiomyomas that appear to be outwardly similar to human uterine fibroid tumors are known to occur on the oviducts of laying hens over two years of age. However, the cellular and molecular similarities of those tumors to human leiomyomas have not been determined. The objective of this study was to characterize the avian tumors and compare them to human uterine fibroids for the purpose of determining the suitability of the aging hen as a model system for the study of the disease. Hens at 5 years of age were examined for the presence of oviduct-associated fibroid tumors. Tumors were found attached to the internal surface of the oviduct, embedded in the oviduct wall, or attached to the exterior of the magnum and isthmus. Tumor and normal oviduct samples were frozen or fixed in formalin for histological and immunohistochemical analyses of biomarkers characteristic of human fibroids including estrogen receptor-alpha (ER-alpha), progesterone receptor (PR), proliferating cell nuclear antigen (PCNA), B-cell leukemia/lymphoma 2 (Bcl-2), transforming growth factor-beta3 (TGF-beta3), insulin-like growth factor-2 (IGF-2), and insulin-like growth factor binding protein-5 (IGFBP-5). Human uterine fibroid samples were acquired and evaluated in comparison to hen oviduct fibroids. The results indicate that laying hen oviduct associated fibroids are similar to human uterine leiomyomas with respect to the defined biomarkers; therefore, it appears the hen may provide a useful model for the study of the disease in humans.