ABSTRACT
Nephrotoxicants are diverse in terms of both structure and mechanism of toxicity. The resulting effects of nephrotoxic insult in fish, however, are often quite similar among classes of toxicants. Ultrastructural alterations of the distal tubules and cells of the head kidney have also been described, and may also be common. The kidney has distinct functions in the two media; functions which are tightly regulated according to the animals' needs. In euryhaline species, it is of particular importance that kidney function can be rapidly altered. The overall appearance of kidneys from different groups of fish varies greatly from a rather simple-looking string of 'loose' tissue in salmonids to a firm well-defined kidney in carp. The interplay between renal and branchial toxicity, the underlying mechanisms of tubular cell death, and the environmental significance of teleost nephrotoxicity are not well understood - but it is clear that a number of common environmental contaminants do cause significant renal toxicity in both freshwater and marine species.
