Epithelial tissue covers or lines body surfaces as well as serving to absorb, filtrate, protect, and secrete various substances. The tissue is classified by the number of cell layers it has (simple=1 cell layer, stratified=more than 1 cell layer) and the shape of the cells (squamous=flat, cuboidal=cube shaped, columnar=column shaped). This microscope slide is a thin section of mammal kidney sectioned at 1.5 to 2 micrometers thick and stained with hematoxylin and eosin.
Thin sections are cut approximately 2 µm (micrometers) as compared to 5 to 10 µm for standard sections. Thin sections show greater clarity of cells and tissues as well as greater detail of cell components. Because of the short depth of field, students should have no problem focusing on thin-section tissues.