Changes of the renal tubular epithelial cell apoptosis as measured by TUNEL staining.

<p><i>A–F</i>, Representative photomicrographs of TUNEL staining from the different treatment groups (original magnification, ×200). In the Sham and ATRA+Sham groups (<i>A</i>, <i>D</i>), little brown staining was seen. In contrast, many TUNEL-positive cells displaying brown staining within the nucleus of apoptotic cells were observed in the IIR, ATRA+IIR and ATRA+RB1 groups (<i>B</i>, <i>E</i> and <i>F</i>). Compared with the IIR group, the number of TUNEL-positive cells displaying brown staining was reduced in the RB1 group (<i>C</i>). <i>G</i>, Apoptotic cells were quantified under high-power magnification by an investigator in a blinded manner and the apoptotic index ( = the number of TUNEL-positive or apoptotic cells/total number of cells counted×100) was calculated. Results are expressed as means ± SEM of apoptotic cells (%) (n = 4, *<i>P</i><0.05 vs. Sham group, #<i>P</i><0.05 vs. IIR group).