A 32-year-old man sustains a laceration to his forearm during a workplace injury. Histological examination of the wound at day 5 post-injury shows predominant fibroblast activity and collagen deposition. Which is the most common type of collagen deposited during this phase of wound healing?

Question

Accepted Answer

C. Type III collagen. ## Collagen Deposition in Wound Healing

### Timeline of Collagen Synthesis

**Key Point:** Type III collagen is the predominant collagen type deposited during the early proliferative phase (days 3–21 post-injury), while Type I collagen becomes dominant in the remodeling phase (weeks 3–12 months).

### Collagen Types in Wound Healing

| Collagen Type | Timeline | Characteristics | Proportion at Day 5 |
| --- | --- | --- | --- |
| **Type III** | Days 3–21 (early proliferative) | Thin fibrils, less tensile strength, more soluble | **70–80% of new collagen** |
| **Type I** | Weeks 3–12 months (remodeling) | Thick fibrils, high tensile strength, cross-linked | Increases gradually; replaces Type III |
| **Type II** | Cartilage matrix | Not involved in skin wound healing | Absent |
| **Type IV** | Basement membrane | Structural, not involved in scar formation | Minimal |

### Clinical Pearl

**High-Yield:** At day 5 post-injury, the wound is in the **proliferative phase**. Fibroblasts are actively synthesizing collagen, and Type III collagen predominates because it is synthesized first and more rapidly. The ratio of Type III:Type I gradually shifts toward Type I over weeks to months during the remodeling phase, which is why scars become stronger and less extensible with time.

### Mechanism

1. Fibroblasts migrate into the wound bed (day 3 onwards)
2. Type III collagen is synthesized first (rapid, thin fibrils)
3. Type I collagen synthesis increases gradually
4. Cross-linking and maturation occur over months
5. Final scar contains ~80% Type I and ~20% Type III collagen

**Mnemonic:** **"3 comes before 1"** — Type **III** collagen is deposited **before** Type **I** collagen in wound healing chronology.

Answer

A. Type I collagen

Answer

B. Type IV collagen

Answer

D. Type II collagen

A 32-year-old man sustains a laceration to his forearm during a workplace injury. Histological examination of the wound at day 5 post-injury shows predominant fibroblast activity and collagen deposition. Which is the most common type of collagen deposited during this phase of wound healing?

Explanation

Collagen Deposition in Wound Healing

Timeline of Collagen Synthesis

Collagen Types in Wound Healing

Clinical Pearl

Mechanism

Practice similar questions

Join our NEET PG community

Collagen Type	Timeline	Characteristics	Proportion at Day 5
Type III	Days 3–21 (early proliferative)	Thin fibrils, less tensile strength, more soluble	70–80% of new collagen
Type I	Weeks 3–12 months (remodeling)	Thick fibrils, high tensile strength, cross-linked	Increases gradually; replaces Type III
Type II	Cartilage matrix	Not involved in skin wound healing	Absent
Type IV	Basement membrane	Structural, not involved in scar formation	Minimal