Figure 4.

Transverse histological section of the corpuscles of Stannius (CS) in Mystus tengara: (a) under controlled condition few of the cells show large nuclei with agranular cytoplasmic contents (solid arrow), (b) under ZnS NP exposure (250 μg/L, d = 3 nm, and t = 60 days) amongst most of the cells with agranular cytoplasm few cells with darkly stained nuclei and granulated cytoplasm (solid arrow) are also visible, (c) under ZnS NP exposure (500 μg/L, d = 3 nm, and t = 60 days) most of the cells have dense granulated cytoplasm (solid arrows) and the nuclear volume of the cells is found to increase along with their condensed status (shown by deeply stained large nuclei), and (d) under ZnS NP exposure (1000 μg/L, d = 3 nm, and t = 60 days) most of the cells have been found with dense granulated cytoplasm with large elongated and dumbbell shaped (solid arrows) hyperactive nuclei with highly condensed chromatin mass (deeply stained). Some large vacuoles are not uncommon. (bc: blood cells, vc: vacuoles.)