Final answer:
The 'feathered edge' refers to a thinly smeared layer of blood cells used for microscopic evaluation, with white blood cells being the larger cells visible. Bacterial cells can also be observed near larger cells like cheek cells, with accuracy in size scale important for clear visualization.
Step-by-step explanation:
The question refers to a blood smear with a 'feathered edge,' which is a technique used to create a thin layer of blood cells on a slide for microscopic examination. During the preparation of a blood smear, the large cells that can be found on the feathered edge are typically white blood cells (leukocytes). These cells are part of the body's immune system and are larger than the more numerous red blood cells (erythrocytes). In a well-prepared blood smear, the feathered edge provides a single layer of cells that is ideal for differentiating and counting the different types of cells present, including observing any bacterial cells that may be present in the sample.
When adding bacterial cells to an illustration or observing them near large cheek cells, it is important to keep the size scale accurate. While cheek cells are typically around 50 to 100 micrometers in size, bacterial cells are much smaller, generally around 0.2 to 2 micrometers. When using an oil immersion objective lens, the size difference becomes even more apparent, allowing for clear visualization of these smaller bacterial cells on or near the larger epithelial cells.