Comparative Study of Ultrastructure of Interlamellar and Intralamellar Types of Henneguya exilis Kudo from Channel Catfish*^†

Abstract

The inter- and intralamellar types of Henneguya exilis Kudo (Myxosporida) infections from channel catfish are similar in spore structure and sporogenesis, but differ in the structure of their plasmodium wall and surface coat and in their relationship with the host cells. The 2 clinical types differ also in the sites of development and growth patterns of plasmodia within a gill filament. Interlamellar plasmodia are limited by 2 outer unit membranes which give rise to both single-and double-membraned pincytic canals. Intralamellar plasmodia are limited by a single outer unit membrane which gives rise to single-membraned pinocytic canals. Interlamellar plasmodia are covered by a fine granular coat of highly variable thicknesses; in some regions there is direct contact between the parasite and cells of the host. There is some evidence that host cell cytoplasm as well as interstitial material are taken in by interlamellar plasmodia. In contrast, intralamellar plasmodia are covered by a fine granular coat of almost uniform thickness, which prevents direct contact between the parasite and cells of the host; probably only interstitial material is taken by these plasmodia.

Gill infection of Leporinus macrocephalus Garavello & Britski, 1988 (Osteichthyes: Anostomidae) by Henneguya leporinicola n. sp. (Myxozoa: Myxobolidae). Description, histopathology and treatment

“…The inter and intralamellar presence of cysts, associated to hyperplasia and inflammation increased the adherence between secondary lamellae. This fact and the hyperplasia of the goblet cells associated with an increase in the mucus production caused respiratory distress syndrome and suffocation of fishes (Dyková & Lom, 1978;Current & Janovy, 1978;Shariff, 1982;Bowser & Conroy, 1985;Kalavati & Narasimhamurti, 1985;. The lesions were similar to those observed in Henneguya infections in perch, Perca fluviatilis (Dyková & Lom, 1978) and in P. mesopotamicus (Alexandrino et al, 1995;Ferraz de Lima et al, 1995).…”

Comparative evaluation of the susceptibility of cultivated fishes to the natural infection with myxosporean parasites and tissue changes in the host

“…The inter and intralamellar presence of cysts, associated to hyperplasia and inflammation increased the adherence between secondary lamellae. This fact and the hyperplasia of the goblet cells associated with an increase in the mucus production caused respiratory distress syndrome and suffocation of fishes (Dyková & Lom, 1978;Current & Janovy, 1978;Shariff, 1982;Bowser & Conroy, 1985;Kalavati & Narasimhamurti, 1985;. The lesions were similar to those observed in H. psorospermica infections in perch, Perca fluviatilis (Dyková & Lom, 1978).…”

Site preference of fish myxosporeans in the gill

“…Recognising the importance of tissue location within the gill, while studying the species Henneguya exilis, Current & Janovy (1978) introduced the concept of inter-and intralamellar infection, which is still widely used by researchers. These terms differ in their mean- ing from those proposed by the present author, as Current & Janovy (1978) failed to distinguish between infections extending to the gill filament and those restricted to the gill lamellae.…”

“…Especially confusing are the terms 'primary lamellae' and 'secondary lamellae', which can be replaced by the words 'filaments' and 'lamellae'. The term 'lamella' creates difficulties primarily in parasitological research, since it is difficult to define whether the terms 'inter-' and 'intralamellar' locations introduced by Current & Janovy (1978) relate to occurrence in the primary or in the secondary lamellae.…”

“…The above authors differentiated types of development on the gill arch, gill filaments and gill lamellae. However, in most species descriptions, only a few papers precisely indicated the site of development, and even the majority of authors dealing with pathology failed to go further than assigning the species that formed plasmodia on the gill filaments to either the intra-or the interlamellar developmental type introduced by Current & Janovy (1978).…”