The key difference between keratinocytes and corneocytes is that keratinocytes are living cells that produce keratin and differentiate into corneocytes while corneocytes are terminally differentiated keratinocytes which are dead cells filled with keratin protein.
There are several cell layers in the epidermis. They are stratum basale, stratum spinosum, stratum granulosum, stratum lucidum and stratum corneum. Stratum corneum is the outer layer of the skin, and it is a sheet comprised of corneocytes. Corneocytes are the outermost cells, which are dead cells filled with keratin. Keratinocytes are the cells that differentiate into corneocytes. Keratinocytes are formed at the basal layer of the cell, and they are the major cell type of epidermis. These are living cells, and they produce keratin protein.
CONTENTS
1. Overview and Key Difference
2. What are Keratinocytes
3. What are Corneocytes
4. Similarities Between Keratinocytes and Corneocytes
5. Side by Side Comparison – Keratinocytes vs Corneocytes in Tabular Form
6. Summary
What are Keratinocytes?
Keratinocytes are the predominant cell type of the epidermis. They are found in the lower layer of the epidermis. These cells are living cells; hence, they are metabolically active. They consist of the cell nucleus and other cell organelles. The major function of keratinocytes is the production of keratin protein. Moreover, keratinocytes make many other proteins.
Figure 01: Keratinocytes
When keratinocytes become mature and migrate outwards, they undergo several transformations. Finally, they differentiate into corneocytes. They lose their nucleus and cytoplasm. Their cell envelope becomes more durable. Finally, they transform into dead dried out hard cells called corneocytes. Keratinocytes are produced by the stem cells in the stratum basale.
What are Corneocytes?
Corneocytes, also known as squames, are terminally differentiated keratinocytes. When transforming keratinocytes into corneocytes, loss of cell nucleus and organelles takes place. Their metabolism ceases. Therefore, corneocytes are dead cells, unlike keratinocytes. Moreover, keratins aggregate inside the corneocytes and gradually become filled with keratin.
Figure 02: Epidermis
When considering the dry weight of corneocytes, more than 80% is occupied by keratin. The cells are approximately 30 µm in diameter and 0.3 µm thick. Corneocytes show a disc-like shape, and they have a large surface area in the horizontal dimension. Corneocytes, together with the intercellular lipid, form a continuous sheet of corneocytes called stratum corneum. It is the outermost layer of the skin, and it acts as a protective barrier or primary barrier between the body and the environment. The lifespan of a corneocyte is about two to three weeks.
What are the Similarities Between Keratinocytes and Corneocytes?
- Keratinocytes and corneocytes are two types of cells found in our skin.
- Keratinocytes produce corneocytes while growing upright.
- They make a protective barrier against harmful substances in the environment.
What is the Difference Between Keratinocytes and Corneocytes?
Keratinocytes are living cells, while corneocytes are dead cells. So, this is the key difference between keratinocytes and corneocytes. Corneocytes originate from keratinocytes. Keratinocytes are found in the basal layer of the epidermis while corneocytes are found in the outermost layer of the epidermis. Moreover, keratinocytes have a nucleus and cytoplasm while corneocytes do not have a nucleus and cytoplasm. Stem cells in the stratum produce keratinocytes while keratinocytes produce corneocytes.
The below infographic shows more comparisons related to the difference between keratinocytes and corneocytes.
Summary – Keratinocytes vs Corneocytes
Keratinocytes and corneocytes are two types of cells found in the epidermis. Keratinocytes are the cells that make keratin protein. They are also found in the basal layer of the epidermis. In contrast, corneocytes are terminally differentiated keratinocytes which are found in the stratum corneum. They are flattened cells having a large surface area. Moreover, they are dead cells filled with keratin. Thus, this is the summary of the difference between keratinocytes and corneocytes.
Reference:
1. Christine Heathman, L.M.T. “Skin Exfoliation”. Dermascope.Com, 2020, Available here.
2. “What is the Stratum Corneum?”. Healthline, 2020, Available here.
Image Courtesy:
1. “Human keratinocytes” By ManatYesbol, Zhansaia, Gaziza Aiatbekovna – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “502 Layers of epidermis” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia