Cytopathological observations on renal tubule epithelium cells in common carp Cyprinus carpio under Trypanoplasma borreli (Protozoa : Kinetoplastida)infection

Cytological alterations in renal tubule epithelium cells of carp Cyprinus c arpio infected with the blood flagellate Trypanoplasma borreli Laveran & Me snil, 1901 were investigated during the course of a laboratory infection of a highly susceptible carp line. With the development of the parasitaemia, a hyperplasia of the interstitial renal tissue was induced, which resulted in a tubulus necrosis. Cytological changes were already seen in tubulus epi thelium cells on Day 7 post injection (PI) of the parasite. The basilar inv aginations of the cells fragmented and a swelling of mitochondria was noted . With increasing parasitaemia, on Days 14 and 21 PI, these changes progres sed up to the loss of the basilar invagination and high amplitude swellings of mitochondria and deterioration of their internal membrane structures. C ells of the distal tubule segment reacted earlier and more rapidly than cel ls of the proximal tubule. The cytological alterations suggested a loss of function of the epithelum cells, which most likely resulted in impaired ion ic and osmotic regulation of T. borreli-infected fishes. Our findings indic ate that in response to the proliferation of the interstitial renal tissue cell structures of the renal tubule cells are altered quickly and in a prog ressive manner.