Dear Karolina,

I have to confess, that I never have done the TEM on cardiac biopsy's, but in general you should not reinvent the wheel. Once biopsy is done, place the sample in the corresponding buffer for further cutting (if you need to divide your sample for several studies - histopathology, biochemistry etc) or directly fix it in a conventional fixative - 2-3% glutaraldehyde. Depending on the size of the sample, you fix it from few hours to a day, then - as standard as it can be: cutting it, if necessary, to 1 mm3; postfixation with OsO4 1-2% (1 hour), dehydration in ethanol series, change to propyleneoxide, end embedding in a resin of your choice through propileneoxide/resin mixture (few hours at least), then pure resin overnight or 24 h and polymerisation 24h at 60°C, for example. If you are interested in a specific region of your sample you have to keep a proper orientation of your sample, 'cause after Os treatment it will be difficult - everything will be black. 

You can also high-pressure-freeze your biopsy's (will work only if it is not thicker then 200µm, and only in case you have Leica HPM-100 freezer) with following freeze-substitution.

And you can use a power of google - quick search "cardiac muscle biopsy", images, shows you few TEM pictures from where you can get on webpages (follow the link)

Good luck!

http://www.utoledo.edu/med/depts/path/emlab/em_diagnostic_services_folder/Muscle_Biopsy.html

Hello! Unfortunately, no.

@Simone Maria Teixeira de Sabóia-Morais 

Your post is disgusting. Why did you do it?

 @Jaroslav Tsytsyura

Thank You!