naco

We do a typical practice of aceto-orsein staining of buccal epithelial cells from female students to visualize Barr bodies under the light microscope. All the illustrations and pictures in the books depict a Barr body located on the edge of the nucleus, but that is not always the case in the students' samples. Given that the cell is a 3D structure, I couldn't explain why the Barr body would localize itself to edge of the nucleus with respect to the viewer's 2D perspective. In a related article's (see link below) introduction, a statement is found saying: "In interphase, the inactive X chromosome (Xi) is found as a condensed heterochromatic Barr body, usually positioned at the nuclear or nucleolar periphery (1-4)." By "usually", does it mean that it is pure luck? Is there any explanation as to why we would have a tendency to see it localized to the edge from our perspective, exactly on the rim of the nucleus, and not just somewhere random? Link to the article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472506/