preservation of fixed sample for TEM

[leahf]

Hi
I keep samples  after fixation (2.5% gluteraldehyde) in 1% gluteraldehyde buffer in plastic tubes. I have been told these samples should be kept in glass tubes.
Is this true?
and why?

[excalibur]

hmmm, never heard that one. The only reason I can think that you should use glass over plastic is for post fixing in osmium tetraoxide. Nasty stuff. It will permeate the plastic.

By 1% glut buffer, do you mean a buffer with 1% glut? This would not be a buffer, but further fixation. And glut fix as a storage medium  will overharden the tissue.

[leahf]

Ahhhhh - that could be it! since i was told this by the guy to whom i pass my samples for further treatment. thanks for clarifying.
I fix in 2.5% gluteraldehyde in seawater (its coral sample) for a couple of hours, then rinse and store in 1% gluteraldehyde in seawater. I was told the presecence of low gluteraldehyde concentration keeps the tissue better...you advise against it?

[excalibur]

Yes, I would not keep tissues stored in a glut solution. If it were my samples, I would rinse in a PBS or cacodylate buffer after fixation. This is similar to you just keeping the samples in sea water, but seawater contains many more salts & minerals than you need. And since the glut kills and preserves the coral, they are no longer in need of sea water.  :wink:

Also, do not store in plain buffer for extended periods of time either, because of bacterial growth. After rinsing in buffer, they should be placed in 70% EtOH. How long before you send the specimens to the other guy? If just a day or two, buffer storage is fine, but any longer, store in alcohol.

Does he post-fix in osmium? If so, tell him if the samples are in alcohol. He will need to rinse it out before placing them in the osmium.

Are these for TEM or SEM?