Fig. 7

Transmission electron microscopy (TEM) of tick midguts shows intracellular Borrelia burgdorferi poised for egress. B. burgdorferi-infected ticks were fed on pathogen-free mice for 24 or 48 h, removed from the host, dissected to obtain tick midguts, processed for TEM analysis, and visualized. Panels 1, 2, 3, 4, 5, 6, and 7 are representative of ~10 midguts at 24 or 48 h of feeding showing B. burgdorferi in the midgut lumen, in the peritrophic matrix, and inside epithelial cells. Panels 8, 9, and 10 show B. burgdorferi inside vesicles adjacent to lipid vesicles and are shown at different magnifications for clarity. Panel 11 shows B. burgdorferi-containing ballooning extrusion of the midgut epithelial cell. B, B. burgdorferi; L, lumen; E, epithelial cells; BL, basal lamina; PM, peritrophic matrix; V, vesicles; LV, lipid vesicles