Histological, Genotoxic, and Biochemical Effects on Cnesterodon decemmaculatus (Jenyns 1842) (Cyprinodontiformes, Poeciliidae): Early Response Bioassays to Assess the Impact of Receiving Waters

Figure 1

Gill filaments histological sections of Cnesterodon decemmaculatus exposed to different treatments for 96 h. Treatments: NC (negative control, MHW); RR (surface water of the Reconquista River); RR+Cd (surface water of the Reconquista River with 2 mg Cd/L); Cd (2 mg Cd/L). Photomicrographs were taken under a Philips XL series 30 or a Carl Zeiss NTS SUPRA 40 scanning electron microscope. Slides (a), (b), and (c) correspond to fish exposed to NC: (a) normal arrangement of primary lamellae (PL) and secondary lamellae (SL) on the gill arc (GA) (350 X); (b) enlarged portion of (a): pavement cell (PV), concentric microridge (MR); mucous cell (MO) (3500X); (c) apical portion of a PL (2000X). Slides (d), (e), and (f) correspond to fish exposed to Cd: (d) primary (PL) and secondary lamellae (SL) (200 X); (e) aspect of a portion of PL with its SL, evident heeling (SC), and disorganization of the epithelium (3500X); (f) apical portion of a PL, showing epithelium disorganization, lifting and swelling of the pavement cells (2000X). Slides (g), (h), and (i) correspond to fish exposed to RR: (g) primary (PL) and secondary lamellae (SL) (350 X); (h) enlarged portion of a PL showing pavement cell (PV), concentric microridge (MR), mucous cell (MO), and chloride cell (CC) (4000X); (i) apical portion of a PL showing edema and abundant mucous cells (MO) flanked by pavement cells (3000X). Slides (j), (k), and (l) correspond to fish exposed to RR+Cd: (j) primary (PL) and secondary lamellae (SL) (500 X), (k) enlarged portion of a PL showing marked epithelium disorganization (5000X); (l) apical portion of a PL showing different degrees of epithelium disorganization, varying from edema to complete disorganization of epithelial architecture (1000X).

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