| occurrence and histological response of raphidascaris acus (nematoda: ascaridoidea) in roach from four lakes differing in water quality. | seasonality and size-related infection of raphidascaris acus larvae from the inner organs and intestine of roach (rutilus rutilus) were studied in 4 lakes of differing water quality and pollution level in central finland between august 1985 and november 1986. the influence of r. acus larvae on the liver and pancreatic tissues of roach was examined histologically in additional material from 1989 and 1990. the inner organs of roach were most heavily infected with r. acus in the eutrophic, polluted ... | 1994 | 8026896 |