WELCOME TO HAIR BIOLOGY 101 IN THE LEARNING CENTER
Welcome to the learning center. The human scalp is comprised of 100 to 150,000 individual hair follicles. These individual hair follicles are grouped together in a manner of a single hair follicle, a 2 hair follicle group, a 3 hair follicle group, all the way to 5 individual hair follicles grouped together. These individual groups are called follicular units or follicular grafts. Below is a sample of a shaved area close to visualize the follicular groups.
The human follicle is comprised of many sophisticated systems all working together to provide hair. The human hair follicle also has growth cycles that are important to know. These cycles include anagen phase, telogen phase, as well as a catagen phase. On the human scalp only do hair follicles remain in the growing phase which is anagen phase. This means the majority of these follicles are growing at an approximate rate of 1/4 inch/0.635 centimeters per month. Scalp anagen phase accounts for 90%. The other 10% go into the telogen phase which is a resting phase. To get to a resting phase the hair must shed. Therefore, on any given day 80 to 100 follicles shed. Some people become alarmed at this when they are shampooing or combing their hair and see hair strands falling of their scalp. However, this is the normal cycle of hair. Outside of the scalp there is a tremendous amount of variability in the cycles of growing and resting. It has been documented that leg and chest hair can easily have 50% in telogen phase and the other 50% in anagen phase. This was proven from early body hair transplants to the scalp. Body hair transplants are moving hair from the beard, leg, arm, or chest to the scalp. Usually it is due to depleted scalp donor follicles from several procedures… Many of the early body hair transplants cycled from anagen to telogen so fast that it looked like a total failure of growth. It was merely the body hair grafts were in resting phase for long lengths of times.
As stated before, the human follicle is comprised of many systems. This “tissue” is unique in that follicles can be cut off from the circulatory system and can live for some time outside of the scalp. The circulatory system for a hair follicle is a single capillary of an oxygenated artery and an oxygenated venus capillary. The image below shows this system.
After a transplant and within 2-3 days this circulatory system is re-established due to biological cues that are secreted from the fresh graft. In fact, this follicle can be re-transplanted again with no harm in certain conditions.
Another unique system is a tiny muscle called the arrector pili that when flexed, can make your hair stand up. This could be caused from getting the “chills” after a fluctuation in temperature or being frightened.
Yet another system is the sebaceous gland system. This system is to secrete natural oils to lubricate the hair shaft and is often the cause of acne outbreaks during hormonal changes.
Hair Transplant Biology and Facts
The most important take away topic from this section in HAIR BIOLOGY 101 is how a transplant works and when do results come in. A hair restoration is not an immediate fix and is not an immediate gratification. In fact, results of a hair restoration no matter the procedure performed are not fully complete until a year has passed. Why? Let’s briefly discuss this but this is definitely an important concept you need to comprehend if you are thinking of having a hair loss procedure.
Follicles or follicle grafts have to be removed from their original home (the back and sides) and placed accordingly in areas of baldness which is the recipient area. When these follicles are extracted they are cut off from nutrients and oxygen via artery capillary. The follicles are still alive and are able to survive quite a long time without nutrients. A study done by myself and a colleague measured the pH of grafts submerged in different media including the typical media saline 0.9% and how the pH changes. We tested Lactated Ringers, BSS Opthalmic Solution, Plasmalyte and saline as a control group. Over time, the pH of the control group dipped dramatically over a 6-hour period. The solutions that did not waiver in Ph were the ones that had a buffering component such as the BSS Opthamic Solution. So theoretically using a buffering media can increase the time the follicles can stay out of the scalp. After 12 hours, there would be a sharp decrease in yield of follicles outside the body in a general setting. Studies have shown the decrease in yields are usually due to lengthy times out of body and/or unregulated temperature conditions. There really is no reason to have grafts outside of the body for more than a few hours. Especially with the advent of FUE it was shown across several reporting clinics that yield was optimal the faster the follicles were placed back into the scalp. learning center
The follicles that are transplanted will seem to grow slightly the first 3 weeks’ post op and then suddenly the transplanted grafts will all begin to shed around the 4-week post op. This shedding is normal and sometimes alarms patients that have not been fully educated about this concept. In fact, your scalp in the transplanted zone also known as “recipient area” will go back to pre op looking conditions. You should have a smooth scalp and it looks as though nothing happened. Underneath the top layer of the scalp the root of the follicle is still there. The transplanted root shed its hair shaft due to the shock of the extracting the follicle out of the scalp. It actually goes into a resting phase. learning center