Fig. 2

Effect of filtering on particle size. Unfiltered particles (Gradia Direct, upper left) dispersed in H₂O were passed through a 5 μm cell strainer, which eliminates the dominant, non-respirable particle fraction (upper right). Resulting particles were mixed with double concentrated KRPG (lower left) or double concentrated F-12 K medium (lower right) to establish cell culture conditions. Phase contrast micrographs taken from the bottom of a 96-well plate after complete sedimentation