Please review the picture in Figure 1. Can you tell which hair is an anagen and which is telogen?
As you may recall from your other reading on our site, growing hairs are in a constant cycle. An anagen hair (active phase) becomes a catagen (intermediate phase), which then becomes a telogen (dormant phase), then back to anagen again.
An anagen hair is an active, growing hair. From the surface, anagen hairs tend to be stronger in hair shaft tensile strength and more pigmented (that is, these hairs have more melanin). On the other hand, telogen hairs are dormant, inactive hairs. These hairs tend to be weaker and less pigmented. The ratio on a normal, healthy scalp is about 90% anagen to 10% telogen. With hair loss, the ratio of anagen to telogen diminishes.
When you review Figure 1 it is nearly impossible to tell the difference between the hairs and their current phase. Only a well trained hair transplant surgery team knows that one has to go deeper than skin level to know which hair is which.
As you can see in Figure 2 (which is the broader picture of the same hairs in Figure 1), the anagen hair on the left has (1) a longer shaft (that is, it goes deeper in the scalp to the sub-cutaneous tissue), (2) the hair bulb, located at the base of the hair (Arrow A) is well developed with a dermal papilla, and (3) has a sebaceous gland (Arrow B), to bathe the hair.
However, the hair on the right is a telogen hair with a much shorter shaft, the hair bulb is called club, and there is no supportive gland.
So what does this mean for you the hair-loss patient?
Since hairs are in a constant cycle, the more anagen hairs transplanted, the sooner results will be noticed, since those hairs are active. Once the telogen hair phase ends and the hair becomes an anagen, then growth will be noticed in that hair. But this will happen at a later time since the hair is not active yet. So be patient.
Secondly, as the photos show, no one can tell with certainty which hair is in which phase without actually removing the hair and viewing it under magnification. Unfortunately, too many hair transplant surgeons claim that they can tell the difference without the removing the hair. Some say that all they need is a magnifying camera to take a picture of the surface the scalp to tell the difference. Even some studies use expensive equipment, such as a phototrichogram, that only adds color to the surface picture, but shows no further information regarding the phase of the hair. As you can see from the pictures, only by removing the hair can you tell which hair is in which phase. Don't be fooled!
Third, after the donor hairs are removed (by the old strip technique) by the surgeon from your scalp, in most offices the technician then is responsible for cutting and trimming down the hair before it is inserted. However, unfortunately, again, too many untrained surgeons have untrained staff who do not fully understand the concept of anagen and telogen hair, so these technicians tend to cut-off the telogen hair and throw it away as useless (even though it is just resting and will begin growing late). That is a wasted hair that could have been used
Most importantly, cosmetically, all too often surgeons and technicians do not realize the concept that the hair is in a cycle and do not notice that there is a telogen hair next to the anagen hair. So this picture is of a two (2) hair follicular unit. But unfortunately, untrained hair transplant teams assume that this is a one (1) hair follicular unit and implant BOTH hairs. This is not that big a problem unless it is implanted in the frontal hair line. Two hairs will eventually grow out rather than the preferred one (1) hair. If this happens often enough, the hairline will look less natural.
Finally, remember this concept of anagen and telogen hairs when looking for products or reading articles about hair regrowth. Always, remember to check to make sure that anagen hairs are regrown and proven to be anagen hairs by biopsy or other direct visualization of the entire hair shaft. In fact, here at IHTI we have developed a product line called Anagenx to stimulate anagen hair growth (more information to follow).