Giant Mitochondria as Possible Bioindicators of Environmental Injuries in Fish Liver.

The effect of hypoxia (80 pHg) and simultaneously applied paraquat (1,1'-dimethyl-4,4-bipyridynum dichloride) was investigated on carp liver using electron microscopic methods. The appearance of giant mitochondria was the most conspicuous alteration in the liver cells. Most of the giant mitochondria were elongated and rod-shaped, often arranged side by side forming clusters beside the nucleus. Crook-like and irregular forms also occured among giant mitochondria. The lenght of the giant mitochondria often was greater than the diameter of nucleus: namely 5-10 µm. The outer membrane of the giant mitochondria was well preserved, but inner membranes (cristae) were usually absent, and a high density matrix filled in the inner space of mitochondria. High power magnification often revealed a regular, filamentous paracristal arrangement in the dense material of the matrix. Swollen giant mitochondria with light matrix and tubular elements also occured in low number. Although fine structural characteristics of carp liver giant mitochondria are not specific for inducing agents (hypoxia + paraquat treatment) the appearance of altered giant mitochondria may be a useful signal for monitoring cell damaging enviromental xenobiotics.