Epithelium, one of the four primary tissues of the body, is characterized by

• A free edge or surface and
• A basal lamina which anchors it to the underlying structure.

Unlike other tissue types, epithelia consist mostly of cells, with little intervening space between the adjacent cells.

• The classification of an epithelial layer is based on the shape of cells that comprise it,
  • Particularly the cells on its free or exposed surface, and
• The number of cellular layers.
• These structural features also reflect the principal activities of the epithelium.

Learning Objectives:

• Learn criteria for identifying the various types of simple and stratified epithelia in light microscopy (LM) preparations.
• Understand how epithelia are classified into simple, stratified and pseudostratified.
• Understand that epithelium forms barriers and compartments by covering and lining the body’s outer and inner surfaces.
• Comprehend the general structure, organization and functions, as well as the specializations within epithelial cells in both LM and EM preparations.
• Understand the relationship between structure and function by comparing epithelia in various organs

Let's start with simple squamous epithelium.