Figure 3.

Mitochondrial staining of untreated U937 cells by TMRM (200 nM), a potentiometric membrane dye which accumulates in the mitochondria. Images (× 60 magnification): the overlay of transmitted light and fluorescent images (A) and the corresponding fluorescent image (B) are presented. The white arrow indicates a TMRM negative U937 cell, also characterized by its morphological appearance in the transmitted light image. Scale bar: 0.02 mm