metamorphosis metamorphosis of the muscular system Great changes take place in the muscular system during metamorphosis. Most larval head muscles are histolysed but some are carried over to the adult, developing the fine structure of adult muscle and aquiring new relationships with different parts of the head. New muscles arise and the sides and floor of the head become traversed by belts of small myoblasts whose origin is uncertain. IDOMAL:0002363 IDOMAL:0002363 idomal_namespace