Dear all,
I'm experiencing the presence of tiny spots on transmission electron microscopy pictures of muscles. Attached you will see 3 pictures of heart tissue in which all the structures (fibers, mitochondria, ER, ecc.) are covered with these very tiny spots. What could be?
For may years I'm always followed the same fixation/embedding protocols without any issue, but sometimes on muscle tissue I have this problem.
I will really appreciate if someone could give some advices.
Thanks!!!
Francesco
According to the older EM literature, these spots are a reaction product of glutaraldehyde, osmium and certain salts. They tend to be more predominant in muscle tissue. Adding 0.05M sucrose to the osmium has been reported to prevent the artifact, also using 1% osmium with 1.5% potassium ferricyanide in buffer tends to be less succeptible to the formation of these granules
Hello, it happened to me when the osmium was already degraded and once when it was also contaminated with heavy metals. The iron in the tissue, and even more so when it is non-heme iron, can generate this type of interference. Make sure that your fixation buffer is well filtered and the glutataldehyde is not precipitated or contaminated. greetings.
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