The Grafted Hair
Hair follicles begin to develop by the third month in utero. We are born with approximately 100,000 hair follicles in the scalp.
Hair follicles grow in random groupings throughout the scalp. These groupings are called “follicular units.” Follicular units contain between 1 and 5 hairs. The average number of hairs per follicular unit is 2.3.
Hair is composed of strong structural protein called keratin. This is the same kind of protein that makes up the nails and the outer layer of skin.
Each strand of hair consists of three layers:
– An innermost layer or medulla which is only present in large thick hairs.
– The middle layer known as the cortex. The cortex provides strength and both the color and texture of hair.
– The outermost layer is known as the cuticle. The cuticle is thin and colorless and serves as a protector of the cortex.
The “hair cycle” has three phases:
Anagen Phase – growth phase
Approximately 85% of all hairs are in the growing phase at any one time. The Anagen phase or “growth phase” can vary from two to six years. Hair grows approximately 10 cm per year, and any individual hair is unlikely to grow more than one meter long.
Catagen Phase – transitional phase
At the end of the Anagen phase the hairs enters into a Catagen phase which lasts about one or two weeks. Approximately 2% of all hairs are in the transitional phase at any one time. During the Catagen phase the hair follicle shrinks to about 1/6 of the normal length. The lower part is destroyed and the dermal papilla breaks away to rest below.
Telogen Phase – resting phase
The resting phase follows the Catagen phase and normally lasts about 5-6 weeks. Approximately 13% of all hairs are in the resting phase at any one time – but this percentage can vary from 4% to 24%. During this time the hair does not grow but stays attached to the follicle while the dermal papilla stays in a resting phase below. Approximately 10-15 percent of all hairs are in this phase at any one time.
At the end of the Telogen phase the hair follicle re-enters the Anagen phase. The dermal papilla and the base of the follicle join together again and a new hair begins to form. If the old hair has not already been shed the new hair pushes the old one out and the growth cycle starts all over again.
Each hair follicle goes through these “hair cycles” 10 to 20 times in a lifetime.
Each hair follicle is a unique and complex structure that exhibits a non-synchronized cyclic life cycle.
Hair plays a role in regulating body heat.
Hair follicles removed from the “donor area” of the scalp can survive for up to 16 hours outside of the body if proper care is taken. Keeping follicles moist in cool saline solution is the first step. (Hair follicles removed from the body and left out to dry will perish within just 3 to 4 hours.)
Placement of the transplanted hair follicles (“grafts”) is important cosmetically and physiologically:
Cosmetically: Graft incisions must mirror the natural growth pattern of native hairs, to yield the best possible result.
Physiologically: Grafts must not be placed so close together or so close to native hairs that blood supply isn’t sufficient to encompass the newly implanted hair follicles. To do so would compromise the viability of not only the grafted hairs but also the surrounding native hairs.
Depending on hair quality, hairs per follicular unit and follicular density, on average, between 120 and 190 graft incisions can be made per square inch.
The first two days following surgical hair transplantation are the most crucial in terms of recovery. Increased blood pressure can actually “pop” a graft out of the skin. It is important to rest, remain as sedentary as possible and refrain from physical activity.
By the third day following surgery, new capillaries (for blood supply) are attaching themselves and growing into the follicle. Surgical recovery is about 90% complete.
By the fourth day, the “bulb” detaches itself from the hair shaft above. In virtually every case, grafted hairs fall out (shed) within the first week or two.
New skin (re-epithelization) occurs after a few days and will occur faster if the skin is kept moist. Topical Copper Peptide aids significantly in this.
By the ninth day, all remaining scabs can be pulled off without difficulty or risk to the follicle. Hair shafts may be attached to these scabs, and they too will be pulled off. This does not affect the bulb beneath the skin. Cosmetic recovery should be almost complete.
Hair growth from the transplanted follicles generally begins at two-and-a-half to three months. But like any “bell-shaped curve,” there are those who experience regrowth as quickly as one month and those who don’t begin until month four.
By the fifth month, usually 90% to 95% of the hairs have begun to grow. (This percentage can be as low as 70% to 75% if regrowth doesn’t begin until month four.)
Transplanted hairs will generally continue to mature during the course of the first year of growth.
Even after 12 months, we find there can be some new growth still occurring.