The main difference between simple squamous epithelium and stratified squamous epithelium is that simple squamous epithelium contains a single cell layer whereas stratified squamous epithelium contains several cell layers. Furthermore, simple squamous epithelium allows materials to pass through either by diffusion or filtration whereas stratified squamous epithelium protects the body against abrasion.

Simple squamous epithelium and stratified squamous epithelium are two types of epithelia that line different cavities of the body.  Simple squamous epithelium occurs in blood capillaries, alveoli of lungs, and the lining of the heart while stratified squamous epithelium occurs in the mouth, oesophagus, and vagina.

Key Areas Covered

1. What is Simple Squamous Epithelium
     – Definition, Structure, Occurrence, Function
2. What is Stratified Squamous Epithelium
     – Definition, Structure, Occurrence, Function
3. What are the Similarities Between Simple Squamous Epithelium and Stratified Squamous Epithelium
     – Outline of Common Features
4. What is the Difference Between Simple Squamous Epithelium and Stratified Squamous Epithelium
     – Comparison of Key Differences

Key Terms

Diffusion, Epithelium, Mechanical Abrasion, Mesothelium, Secretion, Simple Squamous Epithelium, Stratified Squamous Epithelium

What is Simple Squamous Epithelium

Simple squamous epithelium is an epithelium with a single cell layer containing thin, scale-like cells. It lines the vessels of the cardiovascular and lymphatic system. Due to the presence of thin cells, this epithelium allows the passage of chemical compounds through it. Therefore, this epithelium allows the gas exchange in the alveoli, exchange of materials in the kidney tubules, and the exchange of material between the blood and the extracellular fluid.

Figure 1: Simple Squamous Epithelium

Furthermore, simple squamous epithelium forms a surface layer called the mesothelium. Mesothelium is the surface layer of the serous membrane, which lines the internal organs and body cavity. The simple squamous epithelial cells in the mesothelium secrete fluids, lubricating the mesothelium.

What is Stratified Squamous Epithelium

Stratified squamous epithelium is the epithelium with several layers of flat, scale-like epithelial cells. In humans, it is the most common type of stratified epithelium. The upper layers of this epithelium contain squamous epithelial cells. However, the cells in the basal layers can be either columnar or cuboidal.

Figure 2: Stratified Squamous Epithelium

Due to the presence of several cell layers in the epithelium, the main function of the stratified squamous epithelium is to protect the body against abrasion. Thus, this epithelium lines the mouth, esophagus, and vagina where cells can be lost due to mechanical abrasion.

Similarities Between Simple Squamous Epithelium and Stratified Squamous Epithelium

• Simple squamous epithelium and stratified squamous epithelium are two types of epithelia which line difference cavities of the body.
• Both types of epithelia contain flat and scale-like cells.
• Also, all the cells in both types of epithelia are living cells with a dense cytoplasm and a prominent nucleus.
• The cells of the epithelia connect to the underlying connective tissue through the basement membrane.
• Furthermore, both types of epithelia lack blood supply. Therefore, they obtain nutrients through diffusion.
• However, cell junctions are abundant among the cells of both epithelia.
• Besides, both types of epithelia act as boundaries, which provide protection.

Difference Between Simple Squamous Epithelium and Stratified Squamous Epithelium

Definition

Simple squamous epithelium refers to the tissue formed from one layer of squamous cells that line surfaces while stratified squamous epithelium refers to the tissue formed from multiple layers of cells resting on a basement membrane, with the superficial layer(s) consisting of squamous cells. Thus, this is the main difference between simple squamous epithelium and stratified squamous epithelium.

Number of Cell Layers

A major difference between simple squamous epithelium and stratified squamous epithelium is that the simple squamous epithelium contains a single cell layer while stratified squamous epithelium contains several cell layers.

Resting on the Basement Membrane

Moreover, all the cells of the simple squamous epithelium rest on the basement membrane while only the lowermost cell layer rests on the basement membrane in the stratified squamous epithelium.

Occurrence

One more difference between simple squamous epithelium and stratified squamous epithelium is their location. Simple squamous epithelium lines the alveoli, heart, blood capillaries, and lymphatic vessels while stratified squamous epithelium lines the mouth, esophagus, and vagina.

Function

Besides, their functions too make a difference between simple squamous epithelium and stratified squamous epithelium. Simple squamous epithelium allows the materials to pass through the epithelium either through diffusion or filtration while stratified squamous epithelium protects the body against abrasion.

Degree of Protection

Furthermore, the degree of protection is another difference between simple squamous epithelium and stratified squamous epithelium. Simple squamous epithelium provides less protection while stratified squamous epithelium provides a high degree of protection.

Conclusion

Simple squamous epithelium contains a single layer of epithelial cells, which are flat and scale-like. It occurs in the lining of blood capillaries, lymphatic vessels, and alveoli. Furthermore, it allows materials to pass through diffusion and filtration. In comparison, stratified squamous epithelium contains several epithelial cell layers on the basement membrane. It lines the mouth, esophagus, and vagina. The main function of this epithelium is to protect against abrasion. Therefore, the main difference between simple squamous epithelium and stratified squamous epithelium is the number of cell layers, location, and function.

References:

1. “Epithelial Tissue|Anatomy and Physiology.” Lumen Learning, Lumen, Available Here

Image Courtesy:

1. “Epithelial Tissues: Simple Squamous Epithelium (frog)” By Berkshire Community College Bioscience Image Library (Public Domain) via Flickr
2. “Epithelial Tissues Stratified Squamous Epithelium (40230842160)” By Berkshire Community College Bioscience Image Library – Epithelial Tissues: Stratified Squamous Epithelium (CC0) via Commons Wikimedia  

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