Section thickness is an important technical component that can aid in diagnosis. It is necessary to prepare liver biopsy tissue slides so that one cellular layer is visualized microscopically. The ideal thickness for liver biopsy sections is 3-5 μm. Cellular thickness can be verified by focusing the fine adjustment knob (smaller inner knob) on the microscope up and down. When focusing the microscope, one layer of cells should be visible at any field of focus. If you can see more than one layer of cells when focusing, the tissue section is too thick.