Figure 1.

Cytochrome C oxidase (COX) enzyme (A) and COX IV immunohistochemistry (B) in the human control kidney. A, In the cortex, the distal tubules stain most intensely (staining score: 4), and proximal tubules stain as well, but to a lesser degree (staining score: 2). B, Similarly, COX IV immunostain shows higher protein expression in distal tubules than in proximal tubules. C and D, Functional electron microscopy (EM) images of the control kidney showing proximal (C) and distal (D) convoluted tubular COX enzyme activity. Scale bars: A and B = 100 µm; C and D = 2 µm.