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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.

perrywespa wrote: ↑

Sat Jun 26, 2021 8:44 pm

It's been many years since I studied cell anatomy...

The endoplasmic reticulum (ER) was first observed by Porter et al. (1) in thinly spread tissue cultured cells viewed with the electron microscope (EM). With the improvement of EM preparation procedures, numerous reports have followed and have indicated the potentially universal occurrence of this cytoplasmic membranous system in animal cells. Since these reports have resulted only from EM analyses, the endoplasmic reticulum, generally, has been considered a component of submicroscopic size. However, a recent observation by Fawcett and Ito (2) demonstrated that phase contrast images observed in freshly isolated testicular cells were equivalent to EM profiles of the endoplasmic reticulum, and thus removed this organelle from the exclusive realm of submicroscopic analysis.

By the use of an innovation of the tissue culture technique (3), we have observed, in cells of one fetal-lung and two malignant-tissue cultures, structures which appear in every respect to be equivalent to the endoplasmic reticulum as reported by Fawcett and Ito in their phase contrast photographs. Although these structures were not proved by EM techniques to be the endoplasmic reticulum, their relationship to the form and size described by Fawcett and Ito and their location in the endoplasm, indicate that there can be little doubt as to their identity.