I have a strange TEM artifact: bright lines on embedding resin (812 substitute).
Figure 1, lower mag, just resin, no specimen, no staining.
Figure 2, higher mag, low-contrast specimen, stained.
Any ideas what it is?
Great! Have you got a hole in your sample. I follow always artifacts to the hole and see if there frazzles the sample with the artefacts or not!?
Sorry, no holes in sections.
I have to mention acquisition was digital, so no photographic artifacts.
I found no EELS on your homepage and so we have a problem! The plasmaon peak would have given us information about the running of the sample thickness.
It is a biological specimen, no crystals, so no thickness fringes.
That`s clear but EELS works better without diffraction effects. A very old possibility would be stereomicroscopy!?
I agree with Gregory Rudomen. I seem to remember a similar phenomenon in the 1980's when Ciba altered/discontinued the Araldite CY212 ingredient and we went to MY753, fortunately back to CY212..
I agree, it was (unfortunately for me) most probably embedding problem. Cutting with different knives (35 and 45 angle) made no difference.
Thanks a lot.
Header of my question was changed by editor... A lot of words, the same meaning. What for it was done???
Dear Vladimir,
unfortunately chiming in lately.
Agree also with opinions of Gregory & Euan.
Question: would you share with us also i) type of epon substitute (company) and ii) the catalyst / "hardener" you used for polymerisation (DMAE, DMP-30 or else?). Could it be that your resin mixture incorporated water vapour during mixing the components? I have seen such "artifact" once in one of my TEM-preparations long ago....(it could have been the time when substituting original "true" EPON 812/Shell-Monsanto with/by Glycidether 100 (SERVA, Heidelberg,Germany).
Another cause one could think of perhaps would be sectioning artifacts (e.g. poor cutting edge of (diamond?-)knife combined with improper polymerization of resin blocks).
Disclaimer: no affiliation with or any financial interest in the products of the two companies mentioned.
Best regards and hopefully your problem could be solved meanwhile,
Wolfgang
There could be two reasons for such sections. a) The ingredients such as Epon-812, DDSA and MNA may have some moisture which can result in such type of artifacts.b) The ultramicrotomy needs to be done at a very slow speed which can also help to avoid chattering in sections.
I have seen a similar phenomenon and assumed it was a kind of stretching and refolding of the resin. The resin may not be polymerised fully. I have always had very reliable results with TAAB's own resin (Taab Laboratories Equipment, Aldermaston,UK) which is possibly a type of Epon Araldite though they keep the formula a secret. Taab have agencies worldwide.
Thanks everybody for all the comments.
The artifact is still a mystery for me. Specimen is a fine mesh of proteins, its structure is well known to me, so I am sure there was no distortion of specimen at all. Some other things:
1. Artifact can be observed without staining (OsO4 is enough to see specimen).
2. Artifact can be observed without any section stretching (no chloroform, no heat pen).
3. No support film.
4. Specimen morphology looks perfect, i.e. no folds, no stretching.
5. Two diamond knives (45 and 35 degrees) were used with the same result.
6. Nothing unusual was observed while cutting.
7. No damage (cracks, holes) was observed on sections.
8. EmBed 812 (EMS) embedding resin with DMP-30.
OK. Let it be a mystery for now.
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