Flight muscle ultrastructure of susceptible and refractory mosquitoes parasitized by larval Brugia pahangi.

On parasitization with larval Brugia pahangi the infected flight muscle fibres of "resistant" Anopheles labranchiae atroparvus undergo the following ultrastructural changes. The fibres become almost totally devoid of glycogen, their sarcoplasmic reticulum becomes elongate and closely associated with muscle fibrils. These fibrils degenerate and vesicles appear both within the degenerate fibril and within elements of the sarcoplasmic reticulum. Vesicles accumulate around the worm and degenerate to a uniform mass which eventually becomes melanized from its inner edge (next to the parasite) outwards. The infected flight muscle fibres of both "resistant" Aedes aegypti and "susceptible" Aedes togoi are almost totally devoid of glycogen granules, but show no other ultrastructural change from the uninfected state.