Fig. 7

Representative photomicrograph of Nile tilapia spleen. The fish were fed with the control diet or diets containing N. oculata at 5% or 10% for 7 weeks. A Control spleen shows mixed red and white pulp and melanomacrophage aggregation, H&E, 400X. Spleen of tilapia fed on N. oculata at 5% (B) shows extensive, activated melanomacrophage, and (C) many reactive endothelial blood vessels (thin arrows). D, E Spleen of tilapia fed on N. oculata at 10% shows normal histological appearance with minimal lymphoid depletion (thin arrow), other section showing normal architecture with activated melanomacrophages aggregates. H&E, 400X