Desenvolvimento dos tecidos muscular e adiposo em linhagens de tilápia do Nilo Oreochromis niloticus

Abstract

This study aimed to evaluate the muscle and adipose tissues histology regarding to the cells hyper-plasia and hypertrophy of four different strains of Nile tilapia Oreochromis niloticus (Thai, GIFT, Red Stirling and UFLA). It was used 500 fingerlings of each strain, monthly randomly sampled to compose the following standard length classes: 5-10 cm; 10-15 cm; 15-20 cm; and 20-25 cm, with 10 fish per class. Muscle tissue was sampled from the middle portion of the body and immediately after the anal fin. The adipose tissue samples were removed from the viscera. Tissue samples were used to access the amount of cells/area and the diameter of muscle fibers and visceral adipocytes. The GIFT strain had the highest number of muscle fibers / mm². Fish belonging to class 5-10 cm showed greater number of muscle fibers / mm² and lower average diameter of the fibers in relation to the class 10-15 cm (P <0.05). The mean diameter of muscle fibers was higher in 10-15 cm fish compared to 5-10 cm fish, in the Thai strain, and remained unchanged in the GIFT strain. There was a significant effect of strains and fish size for adipocytes perimeter (P <0.05). The development dynamics of muscle and adipose development tissue occurred differently in the four Nile tilapia strains studied.