Difference Between Keratinized and Nonkeratinized Epithelium

The key difference between keratinized and nonkeratinized epithelium is that keratinized epithelium is impervious to water while nonkeratinized epithelium is pervious to water.

Based on the presence of keratin protein, there are two types of epithelia as keratinized epithelium and nonkeratinized epithelium. Keratinized epithelium forms the epidermis of land vertebrates. Nonkeratinized epithelium lines the buccal cavity, esophagus and pharynx. The surface cell layer of keratinized epithelium consists of dead cells and forms an effective barrier. Moreover, it is impervious to water. In contrast, the outermost layer of the nonkeratinized epithelium consists of living cells, and it is a less effective barrier. Moreover, it is pervious to water. The cells of both epithelia increase in size as they migrate from the basal to the prickle cell layer. The synthesis of tonofilaments also occurs in both epithelia.

CONTENTS

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

What is Keratinized Epithelium?

Keratinized epithelium is a stratified squamous epithelium found in skin, epidermis of the palm of the hand and sole of the foot and the masticatory mucosa. Keratinized epithelium forms an effective barrier. The surface layer of it consists of dead cells. Keratin is deposited on the surface. The protoplasm of surface cells is replaced by keratin proteins. Hence, the keratinized epithelium is dry and impervious to water. Moreover, it provides better protection against abrasions.

What is Nonkeratinized Epithelium?

Nonkeratinized epithelium is a stratified squamous epithelium found in lips, buccal mucosa, alveolar mucosa, soft palate, the underside of the tongue, and floor of the mouth. Unlike keratinized epithelium, nonkeratinized epithelium is moist, and it contains living cells in the surface layer.

Most importantly, the structural protein, keratin, is absent in nonnkeratinized epithelium. Hence, it is pervious to water and is a less effective barrier. Moreover, it provides moderate protection against abrasions.

What are the Similarities Between Keratinized and Nonkeratinized Epithelium?

• Keratinized and nonkeratinized epithelium are two types of epithelia based on the presence and absence of the keratin protein.
• Both keratinized and nonkeratinized epithelium consists of stratified squamous epithelium.
• The cells of both epithelia increase in size as they migrate from the basal to the prickle cell layer.
• Moreover, cell shapes change in both epithelia.
• The synthesis of tonofilaments also occurs in both epithelia.

What is the Difference Between Keratinized and Nonkeratinized Epithelium?

The key difference between keratinized and nonkeratinized epithelium is that keratinized epithelium is impervious to water while nonkeratinized epithelium is pervious to water. Moreover, keratinized epithelium is an effective barrier, while nonkeratinized epithelium is a less effective barrier. The surface layer of keratinized epithelium is composed of dead cells which have keratin while the surface layer of nonkeratinized epithelium is composed of living cells and keratin is absent in those cells.

The below infographic details more differences between keratinized and nonkeratinized epithelium in tabular form for side by side comparison.

Summary – Keratinized vs Nonkeratinized Epithelium

Keratinized epithelium and nonkeratinized epithelium are two stratified squamous epithelia. Keratin is deposited in the surface cells of keratinized epithelium while keratin is absent in surface cells of nonkeratinized epithelium. Moreover, in keratinized epithelium, the surface cell layer consists of dead cells while in nonkeratinized epithelium, the surface cell layer consists of living cells. Keratinized epithelium is an effective barrier and provides better protection against abrasions. In contrast, nonkeratinized epithelium is a less effective barrier and provides moderate protection against abrasions. Thus, this is the summary of the difference between keratinized and nonkeratinized epithelium.

Reference:

1. Shetty, Shibani, and Gokul S. “Keratinization and Its Disorders.” Oman Medical Journal, OMJ, Sept. 2012, Available here.

Image Courtesy:

1. “502 Layers of epidermis” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia
2. “Thuc quan” By Nva1991 – Own work (CC BY-SA 3.0) via Commons Wikimedia