ABSTRACT: Fish cells attached to hyphae were observed in brown trout Salmo trutta L. infected with Saprolegnia parasitica. Earlier studies with light microscopy indicated that these cells were lymphocytes and neutrophils and that they were involved in the defence mechanisms against Saprolegnia infections. However, using electron microscopy, we found these attached cells did not show leucocytic characteristics, but instead shared some ultrastructural features with filament-containing cells. The presence of a dense mass of cytoplasmic filaments precludes the leucocytic nature of these cells. How these cells could be involved in cellular defences against fungi is discussed.

KEY WORDS: Saprolegnia infection · Attached fish cells · Cellular defences · Non-leucocytic cells · Salmonid · Ultrastructure

Published in DAO Vol. 32, No. 2 (1998) on March 5
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1998