Difference Between Simple Stratified and Pseudostratified Epithelial Tissue

The key difference between simple stratified and pseudostratified epithelial tissue is the number of layers and the cell attachment to the basement membrane. The simple epithelium has a single layer of cells attached to a basement membrane while stratified epithelium has multiple layers of cells in which only the basal cell layer is attached to the basement membrane; pseudostratified epithelium, on the other hand, has only one cell layer attached to the basement membrane, but it appears as stratified.

Epithelial tissue is one of the four different types of tissues we have. It is important in covering the body, lining the body cavities and composing the glands. Although the epithelial tissue does not have blood vessels, it is innervated in nature. It comprises cell layers tightly connected together. Epithelium fulfils several different functions in our body. It protects our body from radiation, desiccation, toxins, and physical trauma. In the digestive tract, epithelium facilitates nutrient absorption. Furthermore, it secretes sweat, mucus, enzymes and other products of ducts. Based on the number of layers, there are three types of epitheliums as simple, stratified and pseudostratified. In this article, let’s looks at the difference between simple stratified and pseudostratified epithelial tissue.

CONTENTS

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

What is Simple Epithelial Tissue?

Simple epithelial tissue contains a single layer of cells resting on a basement membrane, which is a fibrous network. Based on the shape of the cells in simple epithelial tissue, there are three types of simple epithelial tissues as simple squamous epithelial tissue, simple cuboidal epithelial tissue and simple columnar epithelial tissue.

Simple squamous epithelial tissue has a single cell layer composed of flat polygonal or hexagonal shaped cells. Each cell has a centrally located spherical nucleus and irregular boundaries. Further, this tissue can be seen in the lining of the heart, alveoli, Bowman’s capsule, visceral and peritoneal lining of the coelom. Protection, filtration, absorption and secretion are the main functions of the simple squamous tissue.

Simple cuboidal epithelial tissue has a single layer of cuboidal shaped cells with the same height and width. Further, this tissue can be seen in the pancreatic ducts, salivary glands, along the renal tubule. Simple cuboidal epithelial cells can also be lined with microvilli, which facilitate the function of absorption. General functions of the simple cuboidal epithelial tissue are protection, absorption, secretion and excretion.

Simple columnar epithelial tissue consists of tall column-shaped cells with unequal height and width. The cells contain elongated nuclei situated in close proximity with the basement membrane. Simple columnar epithelial tissue cells also contain goblet cells or secretory cells which help in secretion of various chemicals and fluids. The tissue can be seen along the lining of the stomach, small and large intestine, digestive glands, uterine wall and gall bladder. Its major functions are absorption, secretion and excretion.

What is Stratified Epithelial Tissue?

Stratified epithelial tissue has two or more layers of cells and is the most widespread tissue type lining interior organs and the body cavity. There are three types of stratified epithelial tissue based on the shape of cells. They are stratified squamous epithelial tissue, stratified cuboidal epithelial tissue and stratified columnar epithelial tissue.

Stratified squamous epithelial tissue has cells that are similar to simple squamous epithelial tissue, but they are in several layers. They can be keratinized or nonkeratinized. The outer skin layer has keratinized stratified squamous epithelial tissue. It consists of keratin protein which provides a protective function. Non-keratinized stratified squamous epithelial tissue can be seen in the oral cavity, oesophagus to the stomach junction, anus, rectum, vagina and cervix. In contrast, stratified cuboidal epithelial tissue is present in the ducts of glands (sweat glands, mammary glands) while the stratified columnar epithelial tissue is present in transition areas (junctions) between other epithelial types.

In addition to these, the transitional epithelium is also a type of stratified epithelial tissue. It has cells of varying shapes, and they are stretched along the basement membrane. Its distribution is along the lining of the ureters, urethra, and bladder.

What is Pseudostratified Epithelial Tissue?

Pseudostratified epithelial tissue has a single cell layer. All the cells contact with the basement membrane. But the nuclei are in different layers in the pseudostratified epithelial tissue. The cells of pseudostratified epithelial tissue vary in height. When viewing the epithelial tissue, it appears to be composed of several cell layers as the cells are of different heights. Only the tallest cells reach the surface, but all cells reside on the basement membrane. Due to this illusion, the epithelial tissue is named as pseudostratified.

Most cells have cilia, and they can be seen along the trachea, bronchi and other respiratory structures. The main function of the pseudostratified epithelium is to trap the dust and infectious particles. It also provides protection to those tissues.

What are the Similarities Between Simple Stratified and Pseudostratified Epithelial Tissue?

• They are types of epithelial tissues that form the lining of organs and protect the organs.
• They contain a basement membrane on which the cells reside.

What is the Difference Between Simple Stratified and Pseudostratified Epithelial Tissue?

The key difference between simple stratified and pseudostratified epithelial tissue is that simple epithelial tissue has only one cell layer while stratified epithelial tissue has several cell layers and pseudostratified epithelial tissue appears to have several cell layers despite having only one cell layer.

The below infographic summarizes the difference between simple stratified and pseudostratified epithelial tissue.

Summary – Simple Stratified vs Pseudostratified Epithelial Tissue

Epithelial tissue is a type of tissue which forms the outer covering of the body and forms the lining of the body cavities. The simple epithelial tissue has only a single layer of cells, whereas the stratified epithelial tissue has two or more cell layers stacked upon each other. Pseudostratified epithelium, on the other hand, appears as several cell layers. But, all cells in the pseudostratified epithelium are connected to the basement membrane. So, this is the summary of the difference between simple stratified and pseudostratified epithelial tissue.

Reference:

1. “Epithelial Tissue .” Anatomy and Physiology, OpenStax, 6 Mar. 2013, Available here.
2.“Epithelium.” Wikipedia, Wikimedia Foundation, 19 Sept. 2019, Available here.

Image Courtesy:

1. “403 Epithelial Tissue” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia
2. “Epithelial Tissues Stratified Squamous Epithelium (41994232802)” By Berkshire Community College Bioscience Image Library – Epithelial Tissues: Stratified Squamous Epithelium (CC0) via Commons Wikimedia
3. “Blausen 0750 PseudostratifiedCiliatedColumnar” By Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia