What is the Difference Between Epithelial and Mesenchymal Cells?

Epithelial and mesenchymal cells are two main differentiated cell types in vertebrates that serve different functions and have distinct characteristics. Here are the key differences between them:

Epithelial Cells:

• Uniform cells that form epithelium, which separates the underlying tissue of the body from the outside environment.
• Tightly attached to each other and cover all body surfaces.
• Can be classified into squamous epithelium (flat, irregularly shaped cell layers) and columnar epithelium (taller, polygonal cell boundaries).
• Have apical-basal polarity, intercellular adhesion complexes, and a polarized actin cytoskeleton.
• Upon completion of development, they exert tissue-specific functions.

Mesenchymal Cells:

• Unspecialized, multipotent cells derived mostly from the mesoderm.
• Loosely packed and can move to new positions, providing a vehicle for cell rearrangement and dispersal.
• Lack apical-basal polarity and adhesion complexes, but exhibit an elongated morphology, filopodia, front end-back end polarity, and invasive motility.
• Can differentiate into a variety of mature cell types, such as cartilage, adipose tissue, lymphatic tissue, and bone tissues.
• Play a supporting role in tissues, providing a substrate for epithelial cells.

During certain developmental processes, epithelial cells can undergo an epithelial-mesenchymal transition (EMT), which allows them to assume a mesenchymal cell phenotype, gaining migratory capacity, invasiveness, and elevated resistance to apoptosis. Conversely, mesenchymal cells can convert into epithelial cells, demonstrating a reverse transition process.

Comparative Table: Epithelial vs Mesenchymal Cells

Here is a table comparing the differences between epithelial and mesenchymal cells:

Epithelial cells are uniform cells that form the epithelium, which separates the underlying tissue of the body from the outside environment. They are polarized and organized into sheets of cells, with tight adherence and communication through specialized intercellular junctions.

Mesenchymal cells, on the other hand, are a group of cells with similar morphology and function that make up the mesenchymal tissue, which is a connective tissue from all three germ layers in the gastrula. Mesenchymal cells can differentiate into several mature cell types, such as cartilage, adipose tissue, lymphatic tissue, and bone tissues, making them multipotent stem cells. They exhibit mesenchymal characteristics through changes in junction formation and dissolution and lack the tight organization and apical-basal polarity found in epithelial cells.