WOUND HEALING BY FIRST INTENTION (PRIMARY UNION)

 

INTRODUCTION: Wounds are some of the most common disruptions on the human skin and the leading ports of entry for microbes into the body.  Whether a wound is following a surgical operation, burns or an accidental injury if it is not catered for, it may cause infections from the external environment.  In our discussion here, we are looking at the process through which a surgical and clean wound will take to heal.

This type of healing occurs when there is no contamination of the wound, and the edges of the wound are approximated, thus closing the wound. The best example of this situation is the surgical incision where contamination of the wound is minimized and the wound is closed by suturing, once the wound is sutured, the incision space fills with blood, which contains fibrin and blood cells and which subsequently clots, the surface of this clot becomes dehydrated and forms a scab.

Within 24 hours, neutrophils appear at the edges of the incision and the epithelium at the edges of the incision begins to proliferate, it migrates under the scab and forms a thin continuous epithelial layer.

By 72 hours, macrophages are usually the most numerous inflammatory cells and granulation tissue starts to develop, collagen fibers are present but do not bridge the incision site, the epithelial cells continue to proliferate under the scab and the epidermal covering over the incision becomes thicker.

By day 5, the incision space is filled with granulation tissue and collagen fibers begin to bridge the incision, the epidermis returns to its normal thickness and keratinized architecture.

During the second week, there is continued accumulation of collagen fibers and proliferation of fibroblasts, inflammatory cells, edema disappears, and the process of blanching begins.

By the end of one month, a connective tissue scar is devoid of inflammatory cells and is covered by an intact epidermis.

RELATED;

1. WOUND HEALING BY SECONDARY INTENTION  

2. COMPLICATIONS OF WOUND HEALING  

3. CHRONIC INFLAMMATION

4.  BURNS

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