This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Strength of wound after 2 months is governed by- 
Select and explain. 
A. Collagen cross linking, B. Excess collagen deposition, C. Both 'a' and 'b', D. None of the above
A: Collagen cross linking
Answer: A: Collagen cross linking 
Explanation: Ans. is 'a' i.e., Collagen cross linking Wound strengtho At the end of first week, wound strength is approximately 10% that of normal skin,o Strength increases rapidly over the next 4 weeks.o At the end of third months, the strength reaches a plateau of about 70 to 80% of the normal skin, a condition that may persist for life.So, (Remember following facts)o Tensile strength never reaches the normal strength of unwounded tissue (i.e., 100%).o Maximum strength is achieved by the end of 3 months.o Maximum strength is 70-80% of normal tissue.How does tensile strength change with time ?o During first 2 months it is due to excess collagen deposition.o After that it is due to structural modification of collagen, i.e., cross-linking, increased fiber size.