LIGHT AND SCANNING ELECTRON-MICROSCOPIC CYTOPATHOLOGY OF 3,5-DICHLOROPHENOL IN THE PERMANENT FISH CELL-LINE RTG-2

The permanent fibrocyte-like fish cell line RTG-2 from rainbow trout ( Oncorhynchus mykiss) gonads was investigated by means of light and sca nning electron microscopy with respect to alterations as a consequence of sublethal exposure to 0, 1, 10, 16, 25, and 50 mg/liter 3,5-dichlo rophenol (3,5-DCP) for 24 h, Control RTG-2 cells were spindle-like in shape and almost three times longer than wide. In subconfluent culture s, they displayed widely spread, flat leading lamellae and formed smal l groups. Along the edges of the cell protrusions, numerous retraction fibrils could be identified. Except for shallow ridges and small fold s, the surface of untreated cells was completely smooth, Following exp osure to 3,5-DCP, distinct dose-dependent alterations in cell shape, t he appearance of surface blebs and invaginations, as well as progressi ve retraction of cell extensions could be observed from the lowest tes t concentration. Morphological changes could be correlated to suppress ion of lactate dehydrogenase and reduced neutral red retention capacit y. (C) 1998 Academic Press.