Figure 2

SEM of freeze-fractured L. salmonis and transverse abdominal semi-thin histological section. a) SEM of freeze-fractured louse showing a large xenoma (x) developing beneath the cuticle (cu). The epidermal tissue layer remains uninfected directly beneath the cuticle (white arrows) but has a different more coarse appearance (white asterisk) bordering the haemocoel (h). The xenoma has been fractured open revealing that it is packed with microsporidian spores (s). b) Transverse abdominal semi-thin section from an infected louse. Developing xenomas (x) contain both mature spores (s) and developing stages (d) and can originate from beneath the cuticle (cu) or from the haemocoelic divisions that separate the haemal sinuses (black arrows). The epidermal tissue layer beneath the cuticle remains intact (white arrows). Scale bars a 25 μm, b 50 μm.