Alterations along the Hypothalamic-Pituitary-Thyroid Axis of the Zebrafish (Danio rerio) after Exposure to Propylthiouracil
Figure 6
Representative histopathological effects in thyroidal tissue of zebrafish (Danio rerio) exposed to 25 and 50 mg/L PTU. Exposure to PTU resulted in massive hyperplasia and hyperemia with an increased number of small follicles embedded in adjacent blood capillaries (a, b). In the 25 and 50 mg/L concentration groups, inclusion bodies in the colloid were visible ((c): ▲). At concentrations ≥10 mg/L, severe hypertrophy of thyroid follicles could be detected with stratification and cell crowding (d): One individual in each of the 25 and 50 mg/L concentration groups showed mostly apically located vesicles in the epithelial cells ((e): ▲). Some individuals displayed small follicles scattered across the gills ((f): ▲). Sections of 2 μm thickness stained with periodic acid-Schiff (PAS) and Mayer’s hematoxylin.
