Figure 4
B. burgdorferi progress through the nymphal midgut during feeding in the form of epithelial cell–associated networks.
Representative confocal micrographs of midguts isolated from Bb914-infected nymphs at (A–D) 48 and (E–L) 72 hours after placement; E–H and I–L, respectively, show hypertrophied and undifferentiated regions of 72-hour-fed midguts. Composite images in A, E, and I depict the full thickness of the respective epithelial layers. 3-μm composite images show spirochetes (B, F, and J) at the luminal surface (C, G, and K) midway through the epithelium and (D, H, and L) at the basement membrane. Orthogonal views (y-z and x-z axes) for the 72-hour-fed midguts in H and L show that some spirochetes near the basement membrane (arrows) are in a head-on orientation. The positions of the lumen (Lu) and basement membrane (BM) in each orthogonal view are indicated. The asterisk in the y-z axis view of H denotes a spirochetal network. Scale bars: 25 μm.
