What is the Difference Between Corneocytes and Keratinocytes

The main difference between corneocytes and keratinocytes is that corneocytes are keratinocytes with no nuclei and cytoplasmic organelles, whereas keratinocytes are a primary cell type in the epidermis. 

Corneocytes and keratinocytes are two types of cells that occur in the epidermis. Epidermis is the outermost layer of the skin. 

Key Areas Covered

1. What are Corneocytes
– Definition, Structure, Function
2. What are Keratinocytes
– Definition, Structure, Function
3. Similarities Between Corneocytes and Keratinocytes
– Outline of Common Features
4. Difference Between Corneocytes and Keratinocytes
– Comparison of Key Differences

Key Terms 

Corneocytes, Keratinocytes

What are Corneocytes

Corneocytes are terminally differentiated keratinocytes. They do not contain nuclei or cell organelles. A cornified envelope occurs within the plasma membrane, and it is highly insoluble. Also, corneocytes contain lipids released by lamellar bodies. Additionally, corneocytes form a vertical column of 10-30 cells forming stratum corneum, the top layer of the epidermis mainly composed of corneocytes.

Figure 1: Corneocytes

Moreover, corneodesmosomes are specialized cell junctions that occur in corneocytes. These junctions disintegrate when corneocytes migrate to the top. On the other hand, desquamation is the process of removing corneocytes. Corneocytes renew from the lower epidermis layer, and it is essential as a protective barrier.

Furthermore, corneocytes are an indicator of the regeneration of the skin. When the skin has a faster turnover, the epidermis produces a smaller size of corneocytes. Corneocytes are the last stage of keratinocyte differentiation. 

What are Keratinocytes

Keratinocytes are the epidermal cells that produce keratin. They occur in the deep basal layer of the stratified epithelium of the epidermis. Therefore, these cells are sometimes called basal cells or basal keratinocytes. Typically, 95% of the cells in the epidermis are keratinocytes. Some squamous keratinocytes occur in the mucosa of the esophagus, mouth, corneal, conjunctival, and genital epithelia. The primary function of keratinocytes is to produce keratin. In addition, keratinocytes produce tight junctions with nerve endings of the skin. Furthermore, keratinocytes keep both Langerhans cells and lymphocytes in place.

Figure 2: Keratinocytes

Keratin is the primary protein in the keratinocytes, forming the cell’s cytoskeleton. It serves as a physical barrier between the organism and the external environment, preventing the entrance of pathogens and toxins. It also prevents the loss of moisture and heat from the body. Keratin also forms hair and nails. Keratinocytes serve as immunomodulators, secreting inhibitory cytokines.

Similarities Between Corneocytes and Keratinocytes

• Corneocytes and keratinocytes are two types of cells that occur in the epidermis.
• They serve as a barrier against environmental damage by heat, water loss, UV radiation, pathogenic bacteria, fungi, viruses, and parasites.

Difference Between Corneocytes and Keratinocytes

Definition

Corneocytes refer to a terminally differentiated, anucleate, flattened, dead keratinocyte filled mainly with keratin filaments, has an insoluble envelope of cross-linked proteins, and is connected to other corneocytes by desmosomes. In contrast, keratinocytes refer to a cell of the epidermis that produces keratin, is formed in the basal epidermal layer above the dermis, divides to produce more keratinocytes, and ultimately migrates into the outer protective layers of the skin and undergoes final differentiation into a corneocyte. 

Structure

Corneocytes are keratinocytes without nuclei and cytoplasmic organelles, while keratinocytes arrange in four different layers — the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum.

Occurrence

Corneocytes are the top layer of the epidermis, while keratinocytes occur beneath the corneocytes. 

Function

Corneocytes serve as a physical, chemical, and immunological barrier, while the essential role of keratinocytes is protection, as they form a tight barrier that prevents foreign substances from entering.

Conclusion

In brief, corneocytes and keratinocytes are two types of cells that occur in the skin’s epidermis. Corneocytes are keratinocytes with no nuclei or cell organelles. Also, they appear on the top layer of the epidermis. They serve as a physical, chemical, and immunological barrier to the skin. In comparison, keratinocytes are the cells in the epidermis occurring beneath the corneocytes. They contain four layers: the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. However, the function of the keratinocytes is to serve as a tight barrier, preventing the entry of foreign substances. Thus, this summarizes the difference between corneocytes and keratinocytes.

References:

1. Corneocyte. Corneocyte – an overview | ScienceDirect Topics. (n.d.). 
2. Keratinocyte. Keratinocyte – an overview | ScienceDirect Topics. (n.d.). 

Image Courtesy:

1. “502 Layers of epidermis” By OpenStax College : J. Gordon Betts, Peter Desaix, Eddie Johnson – Own work (CC-BY 3.0) via Commons Wikimedia
2. “Micrograph of keratinocytes, basal cells and melanocytes in the epidermis” By Setijanti H.B., Rusmawati E., Fitria R., Erlina T., Adriany R., Murtiningsih – Own Work (CC-BY 4.0) via Commons Wikimedia