Difference Between Simple and Compound Epithelium

The key difference between simple and compound epithelium is that simple epithelium has a single layer of cells while compound epithelium has more than one cell layer.

There are four major types of tissues in our body which carry out different functions. Among them, the epithelium is an important tissue that lines our body surfaces and internal and external surfaces of body organs. There are two main types of epithelial tissue based on the number of cell layers. They are simple epithelium and compound or stratified epithelium. Simple epithelium always has one cell layer while compound epithelium has more than a single cell layer. Hence, there is a difference between simple and compound epithelium in terms of structure, function, and location.

CONTENTS

1. Overview and Key Difference
2. What is Simple Epithelium
3. What is Compound Epithelium
4. Similarities Between Simple and Compound Epithelium
5. Side by Side Comparison – Simple vs Compound Epithelium in Tabular Form
6. Summary

What is Simple Epithelium?

Simple epithelium is one of the two main types of epithelial tissues. As the name suggests, the simple epithelium has one cell layer. Hence, all the cells of the simple epithelium are attached to the basement membrane. Based on the shapes of the cells, there are four types of the simple epithelium as simple squamous epithelium, simple cuboidal epithelium, simple columnar epithelium, and pseudo-stratified epithelium.

Furthermore, simple epithelial tissue can be seen in the lining of the blood vessels, alveoli, pericardium, kidney tubules, pancreas, glands, stomach, small intestine, trachea, airways, and nose. Simple epithelium mainly fulfills functions such as absorption, secretion, and filtration.

What is Compound Epithelium?

Compound epithelium or stratified epithelium is the second major type of epithelial tissue. It contains more than one cell layer. Hence, only the deepest layer of the compound epithelium is attached to the basement membrane. Furthermore, the compound epithelium can be keratinized. Similar to the simple epithelium, the compound epithelium can be squamous stratified, cuboidal stratified, columnar stratified or transitional epithelium.

Compound epithelium mainly fulfills a protective function. Hence, we can observe them in the esophagus, mouth, sweat glands, mammary glands, male urethra, skin, and urinary bladder.

What are the Similarities Between Simple and Compound Epithelium?

• Simple and compound epithelium are two types of epithelial tissues.
• They rest on a basement membrane.
• Also, both tissues consist of living cells.
• And, these tissues can be classified as squamous, cuboidal or columnar by shape.
• Furthermore, they do not contain blood vessels.
• Hence, they receive nutrition through diffusion from connective tissue underlying the basement membrane.
• These epithelial tissues line the internal and external surfaces of the body while providing protection.

What is the Difference Between Simple and Compound Epithelium?

The key difference between simple and compound epithelium lies in the number of cell layers. That is; the simple epithelium has one cell layer while compound epithelium has more than one cell layer. Moreover, the functional difference between simple and compound epithelium is that the simple epithelium carries out functions such as absorption, secretion, and filtration while compound epithelium has a protective function.

Furthermore, there are four types of simple epithelial tissues as squamous, cuboidal, columnar and pseudo-stratified epithelium and four types of compound epithelial tissues as squamous, cuboidal, transitional and columnar. Hence, we can consider this also as a difference between simple and compound epithelium. A further difference between simple and compound epithelium is the attachment to the basement membrane. In simple epithelium, all cells are attached to the basement membrane. However, in the compound epithelium, only the deepest layer is attached to the basement membrane.

The following infographic presents the difference between simple and compound epithelium comparatively.

Summary – Simple vs Compound Epithelium

Simple and compound epithelium are the two main types of epithelial tissues. The simple epithelium has one cell layer while compound epithelium has more than one cell layer. Thus, this is the key difference between simple and compound epithelium. Moreover, all the cells of the simple epithelium are attached to the basement membrane while in the compound epithelium, only the deepest cell layer is attached to the basement membrane. Furthermore, simple epithelium fulfills functions such as absorption, filtration, and secretion while compound epithelium fulfills a protective function. Thus, this summarizes the difference between simple and compound epithelium.

Reference:

1. “Epithelium.” Wikipedia, Wikimedia Foundation, 9 Apr. 2019, Available here.
2. “Types of Epithelial Tissue: Simple and Compound | Human Body | Biology.” Biology Discussion, 24 July 2017, Available here.

Image Courtesy:

1. “Epithelial Tissues Simple Cuboidal Epithelium (41681552782)” By Berkshire Community College Bioscience Image Library – Epithelial Tissues: Simple Cuboidal Epithelium (CC0) via Commons Wikimedia
2. “Stratified squamous epithelium” By Kamil Danak – Own work (CC BY-SA 3.0) via Commons Wikimedia