During examination of transmission electron microscopy images of skeletal muscle biopsies from patients suffering from different myopathies, sometimes I find somewhat unusual mitochondria with white spots. Initially, I assumed that is some sort of oxidative stress damage or even artifact, yet now I think I could be wrong; usually, in patients with frequent "white spotted" mitochondria, I find more pronounced pathological changes in mitochondria (such as paracrystalline inclusion or onion-like cristae) in other fibers, sooner or later.
That made me think, so I've tried to find similar images in other studies, but to no avail. I have no reasonable explanation as for now. Any ideas?
hello Michał Kulus Though it is not uncommon to see hyperintensities in mitochondria especially in pathologies where there are enlarged mitochondria, your image reminds me of Alpers-Huttenlocher syndrome skeletal muscle mitochondria! I think you are right to think these are oxidative stress related points resulting in focal cristea swelling or vesicular swelling. Were these fresh biopsies processed or frozen stored/fixed biopsies reprocessed for TEM? if the latter then that may explain why the mitos are shrunken a little despite focal swelling. Check Article Correlated three-dimensional light and electron microscopy r...
Dear Rabeah Al-Temaimi, thank you for your response!
Images shown in the mentioned article are somewhat similar to ours, it's quite possible that our mitochondria may also lose their membrane potential. Early or late apoptotic events are also possible, as I find in muscles with severely disorganized myofibrils.
Cristae swelling is rather unlikely (yet still possible) - on image taken on higher magnification (attached below) I cannot see swollen cristae, those hyperintensities seem to be independent of visible cristae location. Specimens for current study were fixed in 2.5% glutaraldehyde right after biopsy - however, I am not present during tissue collection, it's possible that between biopsy and muscle fixation more time passed.
Alpers-Huttenlocher syndrome can be rather excluded - it has early onset and we have adult patients only - although, from what I see, muscle mitochondria looks similar indeed.
Thank you again for your response, it was very helpful! Now I have some foothold for further research.
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