Fig. 4

a−c Histological section of fish gill arch and pseudobranch of control untreated group showing; a Presence of large EMC enclosed by dense fibrous capsule with destruction of the adjacent tissue structures with intense inflammatory cells infiltration (insert box) (×40) b. The cyst wall firm and incorporated in gill arch adipose tissue with intense inflammatory cells infiltration mainly EGCs admixed with mononuclear cells (arrows) and edema (asterisks) (×200). c Intense EGCs infiltration with myocytolysis and necrosis of muscle fibers (×200). d–f Histological section of fish gill arch of treated group showing, d presence of large encysted metacercaria enclosed by dense fibrous capsule with no destruction of the adjacent tissue structures (×40). e Intact adipose tissue with no inflammatory reaction (×100). f Few EGCs infiltration the gill arch with minimal necrosis of myocytes (×100)