Monogeneans in the cephalic lateral line of fish: Histology and SEM analysis

VEGA, ROCÍO; GUAGLIARDO, SILVIA; SEMENAS, LILIANA; VIOZZI, GUSTAVO

Rio de Janeiro

Simposio; 7th International Symposium on Monogenea; 2013

Universidade Federal do Paraná

The lateral line system is a mechanoreceptor organ, which perceives the movement in the water around the fish, and is composed of cephalic and trunk portions. The cephalic lateral line (CLL) is comprised by a system of canals and pores with neuromasts inside, which detect changes in pressure and acceleration of the water entering through the pores. Cryptocephalum petreum and Cryptocephalum spiralis (Monogenea: Dactylogyridae) parasitize the cephalic lateral line canals of Percichthys trucha (perch) in Andean-Patagonian lakes and rivers. These monogenens attach and feed on their host tissues and may cause damage or alterations in the function of the parasitized organ. The aim of this work was to study the parasite position in relation to the anatomy of the parasitized organ and the histophatological tissue reaction. For this purpose, juvenile perches (4 to 6cm standard length) were caught and fixed in 10% buffered formalin. Parasitized and non-parasitized perch heads were sectioned at 5µm, in parasagittal sections and stained with haematoxylin-eosin. Additionally, canals with attached monogeneans were photographed by scanning electron microscope (SEM). SEM photos and histological sections obtained showed ventral anchors penetrating through the tissues of the cephalic lateral line canal walls, and breaking the epithelial cyto-architecture. Furthermore, we observed a partial or a complete occlusion of the lumen of the canals, depending on the size and localization of the monogeneans. Despite of that, we did not observe a compressive atrophy or epithelium hyperplasia. The presence of C. petreum and C. spiralis, have a mechanical effects on neuromasts by slowing water movement within the canals or generating turbulence. Thus, the neuromasts could receive erroneous information about the surrounding environment, affecting the perches in the prey capture or during the escape from predators.