Endoplasmic reticulum visible with phase contrast?

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hans
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Endoplasmic reticulum visible with phase contrast?

#1 Post by hans » Sun Jun 20, 2021 12:43 am

I have been looking at cheek cells quite a bit while setting up various phase contrast stuff I bought over the last few months and notice these fine, fingerprint-like striations sometimes visible. Found this old article while trying to figure out what they were:

George G. Rose, C. M. Pomerat - PHASE CONTRAST OBSERVATIONS OF THE ENDOPLASMIC RETICULUM IN LIVING TISSUE CULTURES

Reichert 1744 40/0.66 objective, unfiltered tungsten illumination, converted to black-and-white in RawTherapee using green channel only:
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hans
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Re: Endoplasmic reticulum visible with phase contrast?

#2 Post by hans » Sun Jun 20, 2021 6:02 am

Similar but with the 43X 0.65 achromat on an older B&L Dynoptic:
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perrywespa
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Re: Endoplasmic reticulum visible with phase contrast?

#3 Post by perrywespa » Sun Jun 20, 2021 11:55 am

Impressive! Thanks for sharing.
Perry
Insatiably curious.

hans
Posts: 911
Joined: Thu May 28, 2020 11:10 pm
Location: Southern California

Re: Endoplasmic reticulum visible with phase contrast?

#4 Post by hans » Sun Jun 20, 2021 8:56 pm

Thanks Perry, still not sure whether this is actually ER but it shows some interesting patterns. I don't have a 100X phase objective for my Microstar IV and was getting poor results with the 97X on the Dynoptic the first time I tried it. Not sure what I was doing wrong but after some more fiddling with illumination the 97X is working better:
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hans
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Re: Endoplasmic reticulum visible with phase contrast?

#5 Post by hans » Sat Jun 26, 2021 5:57 am

After more searching I believe this is microplicae, fine ridges in the cell surface. They are mentioned as a resolution test subject here:
E.D. Salmon, Phong Tran - Chapter 9 High-Resolution Video-Enhanced Differential Interference Contrast (VE-DIC) Light Microscopy
B. Squamous Cheek Cell
Another resolution test for the video camera and the alignment of the DIC optics are squamous epithelial cells scraped from your cheek (Fig. 10). The preparation is made by scraping the inside of your cheek with the tip of a plastic pipette or similar tool and spreading the cells and saliva on the center of a clean number 1.5 22 X 22-mm coverslip. The coverslip is quickly inverted on a clean slide and pressed down to spread the cell preparation into a thin layer. The edges of the coverslip are sealed with a thin layer of nail polish. As seen in the low magnification view in Fig. 10A, the cheek cells are large and flat with the nucleus in the center. The upper and lower surfaces have fine ridges, which swirl around much like fingerprints. Many of the ridges are diffraction limited in width and separated by about 0.5-1 pm. If the microscope is aligned properly, these ridges should be distinctly visible by eye and appear in high contrast by VE-DIC using high-resolution optics (Fig. 10B). The cheek cells are also a good test for the optical sectioning capabilities of the microscope since they are about 2-3 pm thick near the periphery.
The scale factor based on the scale bar in panel B of figure 10 (as attached below) is 55 nm/pixel and for comparison the scale factor in the photo with the B&L 97X in the previous post should be 60 nm/pixel. (Calculated, not actually calibrated with a stage micrometer.)

Some freely-downloadable papers with images, mostly SEM:
Microplicae: Characteristic ridge-like folds of the plasmalemma
Microplicae – Specialized Surface Structure of Epithelial Cells of Wet-Surfaced Oral Mucosa
Prenatal Development of Palatal Surface Structures
Scanning Electron Microscopy in Oral Mucosal Research: A Review

And a search on Science Photo Library returns some pretty results: https://www.sciencephoto.com/search?q=microplicae
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perrywespa
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Re: Endoplasmic reticulum visible with phase contrast?

#6 Post by perrywespa » Sat Jun 26, 2021 8:44 pm

That explanation makes more sense. It's been many years since I studied cell anatomy but I don't remember ER taking up that much volume in the cell. Could be wrong, though.
Perry
Insatiably curious.

hans
Posts: 911
Joined: Thu May 28, 2020 11:10 pm
Location: Southern California

Re: Endoplasmic reticulum visible with phase contrast?

#7 Post by hans » Sun Jun 27, 2021 1:16 am

perrywespa wrote:
Sat Jun 26, 2021 8:44 pm
It's been many years since I studied cell anatomy...
Better than never (unless high school biology counts), I'm just image-searching and guessing...

I looked at some fresh ones paying more attention to depth and it does seem like the structure is very thin and near the surface. That would explain why they are often not obviously visible -- unless a cell ends up with a relatively large surface area to parallel with the cover glass only a narrow strip is in focus at once and the overall structure is not apparent.

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