Abstract
Exposure of experimental or wild animals to dioxins affects their thyroid function and morphology. In the present study, we studied the effect of dioxins on the thyroid gland of the wild Japanese monkey (Macaca fuscata). These monkeys live around human habitats and are taxonomically close to humans. Concentrations of dioxins and related compounds, such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs), were measured in the adipose tissues, liver, and skeletal muscles. Thyroid glands of the same specimens were used for histopathologic analysis and quantitative evaluation of follicular cell hypertrophy by digital image analysis. Each concentration of PCDDs, PCDFs, and Co-PCBs ranged from 0.2 to 26pgTEQ/g-fat. There was no relationship between histopathological changes in thyroid gland and TEQ levels. Moreover, no significant alterations were found in the number of follicles or the size of follicular epithelial cells associated with TEQ levels. We concluded that though wild Japanese monkeys were exposed to dioxins and related compounds in the environment, the observed levels might not affect the morphology and function of the thyroid glands.
