DIC and plastic embedding media

[neal Shields]

This is weird!

I got some new prepared slides from a major german manufacturer the other day and they look different.

It looks like the tissue sample is stuck onto a piece of clear tape and then stuck on the slide and covered with a cover slip.

https://www.flickr.com/photos/196001110 ... ed-public/

From what I can tell, from the internet, this is a process that uses plastic embedding media instead of paraffin. Again, from what I can learn, with paraffin, after the sample is cut, the paraffin is "cleared", dissolved away. The only thing left on the slide is tissue sample.

With this process (please correct me if I am wrong) the embedding media stays and can't be cleared. This process is supposed to make it easier to cut thinner sections.

Here is the rub!

It almost completely eliminates the effect of DIC.

In the picture below, I have set my microscope so the the DIC polarizers are at 90 degrees. In the blank areas of the slide, under the coverslip, I get "exclusion". Black. The black/white border that you see (in the example below) is at the embedding media interface. The black turns white? I thought this might be an example of Bell's Theorem it isn't. I rotated my stage 360 degrees and nothing changes.

https://www.flickr.com/photos/196001110 ... ed-public/

https://www.youtube.com/watch?v=zcqZHYo7ONs

Most of my new slides have good staining and more than enough contrast that I don't need to use DIC. Some of them have no stain and no contrast and are basically garbage. Another interesting data point is, Phase Contrast seems unaffected. It works just fine through the embedding media. This kind of shoots a hole in my theory that this is a refractive index problem.

Does anyone understand what I am seeing?

Neal

[Scarodactyl]

Yeah, DIC doesn't work through a birefringent medium, hence the existence of techniques like plasDIC, hoffman etc.
Likely these slides are being produced as cheaply as possible and mesnt for simple brightfield observation.

[neal Shields]

Thanks that will give me something to google.

Neal