When there is a superficial damage (e.g. cut, burn, or bruise)to the outer (epidermis)skin, why does the scar persist for years, if not for ever, despite the skin continuously shedding millions of dead cells every day?
Asked by Shelton via email
I think your preamble and your question don’t quite match. If you only damage the epidermis there’s little chance of scars. Or even of you noticing for that matter – we scratch the epidermis all the time just by touching things. The epidermis is very thin (about 0.06 mm) and abraisions are quickly repaired and replaced by new skin cells. If you cut deep enough for a scar (as in picture) you’ve damaged at least the dermis and probably deeper tissues too.
Scars form when the layers beneath the epidermis are injured. The damaged cells are are replaced by ‘scar’ cells which are purposed to quickly repair the injury, preventing things like blood leaking out or bacteria and viruses getting in.
What happens to this strip of ‘temporary’ scar cells over the following years and months varies with the location of the damage. In some areas the scar tissue is replaced by normal cells, whereas in others the scar never resolves. Some parts of the dermis are regularly remodelled – fingertips for example – and although you can get scarring there, it is uncommon for it to last for years (unless you keep repeating the trauma). The photo shows an established scar that has probably been there many months. Such a scar is likely to shrink over time but will never be completely removed.
Answered by Lewis Pike