HISTOLOGICAL-CHANGES IN THE SWIMBLADDER WALL OF EELS DUE TO ABNORMAL LOCATION OF ADULTS AND 2ND STAGE LARVAE OF ANGUILLICOLA-CRASSUS

In severe Anguillicola crassus infection of eels, adult helminths and 2nd stage larvae staying in the swimbladder lumen may occasionally get , through minor lesions of the tunica interna, into the subserosa of t he swimbladder wall where they die and disintegrate. A thin connective tissue capsule is formed around the helminths that behave as foreign bodies in intercellular location, while the lacunas of the surrounding loose connective tissue comprise melanin-containing macrophages. In t he environment of the 2nd stage larvae the formation of giant cells is a typical finding.