Figure 3.

Optical light micrographs (differential interference contrast, 40×) of the samples of (a) freeze-dried B. thuringiensis cells and endospores and (b) freeze-dried B. subtilis endospores. The regions that were analysed with waveguide-based imaging are indicated by dashed black frames and labels (A), (B), (C) and (D) in both images. The bacteria and remnant cell material in (a) are mainly rod shaped (white arrow heads). Smaller spots are likely to be isolated endospores (black arrow head). An isolated endospore is indicated in (b) by a black arrow head.