Immunofluorescence of Anopheles gambiae abdomen at 24 h post-blood meal. Paraffin-embedded sections were incubated with sera from naïve mice (A) or mice immunized with AgAper1 (B) as primary antibody, and with anti-mouse IgG-FITC as secondary antibody. Arrow in B shows AgAper1 fluorescence within the peritrophic matrix. Mounting media containing DAPI was used for nuclear staining of epithelial cells. Images were taken with a monochromatic camera using DIC, 480 nm, and 546 nm light. They were then false-coloured and merged to produce a single image. EP: epithelium; PM: peritrophic matrix; LM: midgut lumen containing undigested red blood cells. Magnification: 200×.