Development of newly formed nephrons in the goldfish kidney following hexachlorobutadiene-induced nephrotoxicity.

New nephrons developed in goldfish, Carassius auratus, several weeks following hexachlorobutadiene-induced (HCBD) nephrotoxicity. Basophilic clusters of presumptive nephrogenic cells incorporated 5-bromo, 2'deoxyuridine (BrdU) one week after HCBD injection, indicating initiation of DNA synthesis. These clusters, like renal vesicles in the developing kidney, elongated, fused with collecting ducts and developed into immature nephrons during the next 2 weeks. Stereologic quantification showed the volume percent of the kidney occupied by the developing nephrons was greater in HCBD-treated fish 2, 3, 4, and 10 weeks after injection than in the control fish. The presence of large numbers of developing nephrons may provide a marker for renal injury in fish from contaminated waterways.