Figure 4

Muscular atrophy in O. unilateralis s.l infected ants. A) and B) are transmission electron micrographs (TEM) of infected ant mandible muscles. C) TEM shows uninfected muscles. The interfibrillar spaces (IFS) and reduced mitochondria (M) are evident in A & B. The z-line is thinned in A) and in B) an example of a broken z-line is shown by the white arrow. C) shows healthy muscle with prominent sarcoplasmic reticula (SR) and mitochondria. D) is a TEM of the mandible muscle of an O. unilateralis infected ant. The fibers are stretched and tearing is evident as lines running perpendicular to the sarcomeres. The large irregular structures between the muscle fibers are fungal cells. Note the impressions (white arrow) formed where they meet the muscle. The internal structures of the fungal cells have not been preserved using our method and the large white area within these cells reflects that and is therefore an artefact of fixing. E) Quantification of atrophy (mean (+/- SE) percent of interfibrillar space in the muscles cells) in healthy and infected ants. The difference is significant (see text).