12-03-2013, 08:56 PM
Why does hair go into a "resting phase" after being transplanted?
I've been told that it's due to the "shock" of the procedure, but I want to understand what that means from a biochemical viewpoint.
12-06-2013, 02:36 PM
Not a chemistry major so not sure if my reply will be "biochemical".
Here's the deal. Yes it is the "corresponding trauma" from HT surgery that causes shock loss. Sympathetic shock loss is different from permanent shock loss. Sympathetic shock loss will grow back after the follicles rest approximately three months. Permanent shock loss can occur when the underlying follicles are "transected" from the recipient sites created or they are transected from dissecting/trimming of the grafts. Permanent shock loss can also occur to the more weaker diffused native hair that was on its way out. Some call that vellus hair.
But the resting phase is simply that part of the cycle following the growing phase. The full cycle tri-intervals are growing (anagen), resting (telogen), and then shedding (catagen). They behave in that order.
So it's primarily the initial trauma that causes the follicles to retreat to the resting phase. Think of it as what happens to deciduous trees. Every year at autumn the temperature drops significantly. This shocks the tree and then the tree goes into a resting (dormant) phase and then sheds it leaves.
The deciduous tree will remain dormant until conditions change, meaning, a rise in temperature. Once that occurs, the tree springs into the new growth cycle and begins growing leaves again.
IMHO, the resting phase in hair follicles can be a defensive move as a result of the trauma. Apart from trauma, they move normally between their phases as scheduled by their genetic time clock. Many of the existing native hair follicles are shocked as well and why they also retreat after surgery. But for the most part, this is the sympathetic shock loss that I spoke of earlier.
In addition, the transplanted hair follicles shed and rest because once the follicles are removed from the scalp, their blood supply is interrupted which is their life-line. Ischemia reprofusion sets in immediately and the longer the follicles are left out of body, they begin to deteriate fast just as any form of flesh/tissue without a life line (blood supply).
Lastly, the fluids injected into the scalp during the procedure can also cause some of the hair follicles to retreat and rest.