Figure 1

Histopathological analysis of zebrafish brain tissues after 7-day TBT exposure. (A) Schematic illustration of the zebrafish brain. The dashed line indicates the coronal sectioning plane through the forebrain, encompassing the telencephalon and diencephalon, used for histological evaluation. (B) Control group showing intact brain tissue architecture. The 20 ng/L TBT group exhibited largely preserved morphology with only minor alterations. In the 100 ng/L TBT group, nuclear swelling and reduced cell density were observed (green arrows). The 500 ng/L TBT group displayed severe histopathological damage, characterized by extensive vacuolation (red arrows) and tissue atrophy (H&E staining; scale bar = 50 μm; n = 3). (C) Quantitative analysis of TBT-induced histopathological changes in zebrafish brain tissue. Neuronal density (cells/0.1 mm²) and tissue vacuolation index (%) across different TBT exposure concentrations (CK, 20, 100, and 500 ng/L). Data represent mean ± SD (n = 3). ns (not significant), * p < 0.05, *** p < 0.001 compared to control group.