For example, a study investigating the consequences of a single-prolonged stress exposure in an animal model of PTSD reported on stress-induced increase of apoptotic cells in the hippocampus, together with release of cytochrome c from the mitochondria into the cytosol and with morphological abnormalities of the mitochondria (i.e., vacuolar degeneration, cristae fragmentation, exterior membrane disruption, and swollen mitochondria) (Li et al., 2010). The gene discussed is CYCS; the disease is post-traumatic stress disorder.