Marco António Campinho

1 Introduction Recently, there has been increasing concern regarding the occurrence, fate, and toxic effects of pharmaceutical residues in the aquatic environment (1–5). To date, wastewater treatment plants have rarely been explicitly designed to filter drugs, and thus residual amounts have been discharged directly into the environment without any adequate restrictions (6). This has led to the continuous entry and accumulation of pharmacologically active substances in the aquatic environment.

1 Introduction Three centuries after the initial anatomical description of the thyroid gland (1), L-triiodothyronine (T3) was recognized as the active form of thyroid hormones (THs) (2). Subsequent studies have continued to unveil the functional roles of TH. The identification of nuclear TH receptors (nTR), and the elucidation of their transcriptional properties (3) unlocked new vistas for TH research in most tissues.

Anna Crescenzi1† and Zubair Baloch2*† 1Pathology, University Campus Bio-Medico of Rome, Fondazione Policlinico, Rome, Italy 2Pathology & Laboratory Medicine, University of Pennsylvania Medical Center, Perelman School of Medicine, Philadelphia, PA, United States The use of immunohistochemistry cannot be underestimated in the everyday practice of thyroid pathology.