Final answer:
Chemical stains in microscopy, such as viability stains that fluoresce green for live cells and red for dead cells, improve cell visibility by enhancing contrast and allowing for effective cell identification under a microscope. By applying chemical stain to cells, we can improve c) Cell visibility.
Step-by-step explanation:
Chemical stains are used extensively in microscopy to enhance the visibility of cells and their structures. While using a counting chamber, it is difficult to differentiate between live cells, dead cells, and debris under a microscope due to the lack of contrast. However, viability stains developed for fluorescence microscopy can distinguish between viable and nonviable cells because they interact differently with the cellular components depending on the integrity of the cytoplasmic membrane.
The primary stain, which generally fluoresces green, stains both live and dead cells. In contrast, the secondary stain, appearing red, can only enter cells with a damaged cytoplasmic membrane. Thus, live cells display a green fluorescence, while dead cells show red. This differential staining enhances the contrast and enables the visualization of cells, improving their overall visibility under a microscope.