Hepatopancreas Structure of Palaemonetes Argentinus (Decapoda, Caridea) Fed Different Levels of Dietary Cholesterol

Abstract

Cholesterol is not synthesized "de novo" in crustaceans and it constitutes an essential nutrient for growth and survival, with an optimum dietary amount. In this study the effect of dietary cholesterol on hepatopancreas structure of Palaemonetes argentinus was evaluated. Individuals from Los Padres Lagoon (Mar del Plata, Argentina; 37°57'S, 57°44'W) were maintained in aquaria with a diet containing three cholesterol levels (0.4, 0.8, and 1.2%). After 60 days, the hepatopancreas from individuals in intermolt, premolt and postmolt were removed and processed by using standard histological techniques. No differences were found in molting rate and growth. The most important alterations were observed in postmolt prawns fed the 0.4% cholesterol diet. Besides the typical desquamated degeneration in postmolt, haemocytic infiltration, cellular dysplasia and necrosis were present. In all stages, R-cells showed hypervacuolization in prawns fed 0.8 and 1.2% cholesterol diets. The tissular changes related to the molt cycle are similar to those observed in wild prawns.