Ultrastructural changes in blood cells in the hematopoietic organs of Lake Baikal fish exposed to phenol

Baikal Lake fish: stone sculpin (Paracottus knerii), yellowfin (Cottocomephorus grewigkii) and perch (Perca fluviatilis) were exposed for 14 days to phenol (6mg˖L-1). The reaction of blood cells in all studied species had a similar character, whilst, also revealing distinctions. Fast activation of immune processes was found in the pelagic yellowfin. These changes were slower at the coastal stone sculpin. Quantitative changes of blood cells were minor in the coastal nonendemic perch. After four days of exposure, the cells of fish showed signs of destructive processes: strong vacuolization of cytoplasm and partial destruction of the cell membrane. In the cell nucleus the chromatin was condensed, the perinuclear space had expanded and the nuclear membrane had been partly destroyed. In another experiment, stone sculpin and perch were first exposed to phenol for 30 days and then they were kept for another 30 days in water without phenol. In the kidneys and spleen of stone sculpin the processes of lymphopoiesis were observed, whereas in perch the processes of lymphopoiesis and myelopoiesis occurred.