Figure 1. Inner membranes of live mitochondria under a STED microscope imaged using the MitoPB Yellow fluorescent marker molecule created by researchers at the Institute of Transformative Bio-Molecules (ITbM) at Nagoya University. The outer membranes of the mitochondria are invisible. The marker molecule can withstand the STED beam for a relatively long time, which allows time-lapse imaging of the live subject. Sample preparation is much easier for an optical microscope than a Transmission Electron Microscope (TEM), requiring about an hour rather than a day. Cells cannot be imaged alive using TEM. The mitochondria have been treated with a reagent that suppresses DNA replication, inducing dysfunction, in order to see their survival (left) and dying (right) processes. Being able to see the dysfunction processes occurring inside mitochondria will lead to a better way of diagnosing human mitochondrial disease - and perhaps even a cure.