A coho salmon Oncorhynchus kisutch (Walbaum) was found to develop lesi
ons associated with so called X-cells propagating in the liver parench
yma. The ultrastructural features, insufficient to determine the origi
n of X-cells, corresponded to those found in pseudobranchial tumours o
f Atlantic cod by Watermann & Dethlefsen (Helgolander Meeresunters. 35
: 231-242, 1982).