The key difference between epithelialization and granulation is that epithelialization is a part of wound healing which forms a new epithelial surface on the open wound while granulation is the process of forming new connective tissue and blood vessels during wound healing.
Epithelialization and granulation are two processes linked to wound healing. Epithelialization covers ruptured epithelial surfaces. Hence, it creates a barrier to cover the wound and prevents the entering of microorganisms and other pathogenic substances. On the other hand, granulation forms new connective tissue and blood vessels to fill the wound completely. Thus, both epithelialization and granulation are important processes.
CONTENTS
1. Overview and Key Difference
2. What is Epithelialization
3. What is Granulation
4. Similarities Between Epithelialization and Granulation
5. Side by Side Comparison – Epithelialization vs Granulation in Tabular Form
6. Summary
What is Epithelialization?
Epithelialization is the process of covering open wounds with new epithelial surfaces. Hence, it is an essential process in wound healing. Moreover, this process involves both molecular and cellular processes. They are responsible for the initiation, maintenance, and completion of epithelialization. Thus, this results in successful closure of wounds, creating a barrier between the wound and the external environment.
Figure 01: Wound Healing Process
Absence of epithelialization results in improper wound healing. Therefore, causing wound infection, later leading to critical clinical consequences known as chronic wounds. In chronic wounds, re-epithelialization doesn’t take place. Moreover, failure in maintenance keratinocyte barrier contributes to the reoccurrence of wounds. Research in epithelialization process helps to provide new therapeutic approaches in wound healing.
What is Granulation?
Granulation or granulation tissue is a new connective tissue that forms during the wound healing. The connective tissue contains microscopic blood vessels. Hence, granulation is a process of forming new connective tissue, covering the wound surface. Granulation occurs from the base of the wound. Hence, it has the capacity to fill wounds of any size.
Figure 02: Granulation
During the migratory phase of wound healing, granulation tissue appears in dark pink/ light red colour and is moist, bumpy and soft to touch. It consists of a tissue matrix with different types of cells. These cells help in the formation of extracellular matrix or in immunity and vascularization. The tissue matrix of granulation tissue consists of fibroblasts. The major immune cells present in the granulation tissue include macrophages and neutrophils.
What are the Similarities Between Epithelialization and Granulation?
- Both epithelialization and granulation are two processes of wound healing.
- Both processes use different types of cells for wound healing.
- Moreover, they prevent the occurrence of chronic wounds and other clinical problems associating wounds.
- Also, they occur immediately after rupturing of epithelia and other tissues during a wound.
What is the Difference Between Epithelialization and Granulation?
Epithelialization is a process of covering wound surfaces while granulation is a process of forming new connective tissue during the wound healing. So, this is the key difference between epithelialization and granulation. Granulation involves different cells, including immune cells (macrophages and neutrophils) and fibroblast cells. But epithelization involves only keratinocytes.
Moreover, a further difference between epithelialization and granulation is that granulation occurs from the base of the wound, while epithelialization occurs at the wound surface.
The below info-graphic presents more information regarding the difference between epithelialization and granulation.
Summary – Epithelialization vs Granulation
Both epithelialization and granulation are two processes in wound healing. Epithelialization covers wound surfaces with keratinocytes whilst granulation forms new connective tissue from the base of the wound. So, this is the key difference between epithelialization and granulation. Also, in chronic wounds, re-epithelialization doesn’t take place. In summarizing the difference between epithelialization and granulation, granulation involves many cells, including immune cells and fibroblasts, while epithelialization involves only one major type of cell – keratinocytes.
Reference:
1. “Granulation Tissue: Definition, Function & Structure.” Biology Dictionary, 1 July 2017, Available here.
2. Pastar, Irena, et al. “Epithelialization in Wound Healing: A Comprehensive Review.” Advances in Wound Care, Mary Ann Liebert, Inc., 1 July 2014, Available here.
Image Courtesy:
1. “Wound healing phases” By Mikael Häggström – Own work (from the template Logarithmic time scale – milliseconds to years.svg) (Public Domain) via Commons Wikimedia
2. “Granulation tissue in an infected wound, HE 2” By Patho – Own work (CC BY-SA 3.0) via Commons Wikimedia