Growth cycle of hair follicle..!!

The growth of human hair occurs everywhere on the body except for the soles of the feet, the inside of the mouth, the lips, the backs of the ears, the palms of the hands, some external genital areas, the navel, scar tissue, and, apart from eyelashes, the eyelids.[1] Hair is a stratified squamous keratinized epithelium made of multi-layered flat cells whose rope-like filaments provide structure and strength to the hair shaft.

The protein called keratin makes up hair and stimulates hair growth.

Hair follows a specific growth cycle with three distinct and concurrent phases: anagen, catagen, and telogen. Each phase has specific characteristics that determine the length of the hair.

The body has different types of hair, including vellus hair and androgenic hair, each with its own type of cellular construction. This varied construction gives the hair unique characteristics, serving specific purposes, mainly warmth (redundant in modern humans) and physical protection.[2] Most humans develop the longest thickest hair on their scalps and (mostly observed in males) faces. This hair will usually grow to several feet before terminating, but many humans develop much longer hair.

1CB29425-753B-4DCA-BB54-B3830019D823    The first three phases — anagen, catagen, and telogen — cover the growth and maturation of hair and the activity of the hair follicles that produce individual hairs. During the final, or exogen, phase, “old” hair sheds, though usually, a new hair is getting ready to take its place.

Each phase has its own timeline, which can be affected by age, nutrition, and overall health. That means there are steps you can take along the way to help ensure that your hair follows a healthy growth cycle

1. Anagen: Growing phase

The stages of hair growth begin with the anagen phase. It’s the longest phase, lasting about 3 to 5 years for the hairs on your head, though for some people a single hair could continue growing for 7 or more years.

Fortunately, the anagen phase differs with different types of hair. For example, the anagen phase for eyebrow hairs and pubic hairs is much shorter than the phase for your scalp hairs.

During the anagen phase, your hair follicles are pushing out hairs that will continue to grow until they’re cut or until they reach the end of their lifespan and fall out. At any time, about 90 percentTrusted Source of the hairs on your head are in the anagen phase.

2. Catagen: Transition phase

The catagen phase starts when the anagen phase ends, and tends to last about 10 days or so. During this chapter, hair follicles shrink and hair growth slows. The hair also separates from the bottom of the hair follicle, yet remains in place during its final days of growing.

Only about 5 percent of the hairs on your head are in the catagen phase at any given time.

3. Telogen: Resting phase

The telogen phase typically lasts around 3 months. An estimated 10 to 15 percent of your scalp hairs are in this phase.

Hairs don’t grow during the telogen phase, but they don’t usually fall out either. The telogen phase is also when new hairs start to form in follicles that have just released hairs during the catagen phase.

Some health experts consider the telogen phase the shedding phase, as well, but many scientists have divided this stage into two parts: the telogen and exogen stages.

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4. Exogen: Shedding phase

The exogen phase is essentially an extension or a part of the telogen stage of hair growth. During the exogen phase, hair is shed from the scalp, often helped along by washing and brushing. Losing 50 to 100 hairs per day during the exogen phase is normal.

During the exogen phase, which can last about 2 to 5 months, new hairs are growing in the follicles as old hairs fall away.

The hair follicle is a tunnel-like segment of the epidermis that extends down into the dermis. The structure contains several layers that all have separate functions. At the base of the follicle is the papilla, which contains capillaries, or tiny blood vessels that nourish the cells. The living part of the hair is the very bottom part surrounding the papilla, called the bulb. The cells of the bulb divide every 23 to 72 hours, remarkably faster than any other cell in the body.

Two sheaths, an inner and outer sheath, surround the follicle. These structures protect and form the growing hair shaft. The inner sheath follows the hair shaft and ends below the opening of a sebaceous (oil) gland, and sometimes an apocrine (scent) gland. The outer sheath continues all the way up to the gland. A muscle called an erector pili muscle attaches below the gland to a fibrous layer around the outer sheath. When this muscle contracts, it causes the hair to stand up which also causes the sebaceous gland to secrete oil.

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The sebaceous gland is vital because it produces sebum, which conditions the hair and skin. After puberty our body produces more sebum but as we age we begin to make less sebum. Women have far less sebum production than men do as they age.
The hair shaft is made of a hard protein called keratin and is made in three layers. This protein is actually dead, so the hair that you see is not a living structure. The inner layer is the medulla. The second layer is the cortex and the outer layer is the cuticle. The cortex makes up the majority of the hair shaft. The cuticle is a tightly formed structure made of shingle-like overlapping scales. It is both the cortex and the medulla that holds the hair’s pigment, giving it its color.

History of hair transplant – How it started..!!

The modern era of hair transplantation in the western world was ushered in the late 1950s, when New York dermatologist Norman Orentreich began to experiment with free donor grafts to balding areas in patients with male pattern baldness.
This technique involved taking large punch grafts in which they would harvest dozens of hairs from the back of the scalp and then transplant those hairs to the front of the scalp. Since this was the first technique available, there was nothing to compare it to. Unfortunately, the results of this technique gave an unnatural appearance of dozens of circular hair tufts separated by large spaces rather than the normally spaces individual hair follicles of the natural hairline.

The modern hair transplantation procedure was pioneered in the early 1990s by Dr. Bobby Limmer who was the first to perform hair transplantation using follicular unit transplantation (FUT). Modern hair transplantation is based on transplanting follicular units, which are natural groups of hair follicles which grow in groups of 1 to 4 hairs, with the average group of about 2 hairs. FUT involves doing a strip excision on the posterior scalp and then using a stereomicroscope to dissect the strip into individual follicular units. Simultaneously, recipient sites are carefully created by a hair transplant surgeon on the recipient area on the hairline or vertex scalp. The follicular units are then carefully transplanted into the recipient area using specialized forceps. There are no sutures required and the body’s clotting factors hold the hairs in place. Another modern technique which was developed after FUT is called FUE, or follicular unit extraction. In this technique, individual follicular units are harvested from the posterior scalp using either a manual or a motorized instrument. These follicular units are then transplanted into the recipient sites in the frontal hairline/vertex scalp in a similar fashion as in FUT procedures.
E2469218-4C32-4035-A444-1699C4B29EBF 4E4FF7AB-CCAD-4DC4-84F3-22026A989452Hair transplantation is a surgical technique that removes hair follicles from one part of the body, called the ‘donor site’, to a bald or balding part of the body known as the ‘recipient site’. The technique is primarily used to treat male pattern baldness. In this minimally invasive procedure, grafts containing hair follicles that are genetically resistant to balding (like the back of the head) are transplanted to the bald scalp. Hair transplantation can also be used to restore eyelashes, eyebrows, beard hair, chest hair, pubic hair and to fill in scars caused by accidents or surgery such as face-lifts and previous hair transplants. Hair transplantation differs from skin grafting in that grafts contain almost all of the epidermis and dermis surrounding the hair follicle, and many tiny grafts are transplanted rather than a single strip of skin.

8D41988E-F1F1-4C68-93CC-675B3D3712B2Since hair naturally grows in groupings of 1 to 4 hairs, current techniques harvest and transplant hair “follicular units” in their natural groupings. Thus modern hair transplantation can achieve a natural appearance by mimicking original hair orientation. This hair transplant procedure is called follicular unit transplantation (FUT). Donor hair can be harvested in two different ways: strip harvesting, and follicular unit extraction (FUE).

Pre-operative assessment and planning
At an initial consultation, the surgeon analyzes the patient’s scalp, discusses their preferences and expectations, and advises them on the best approach (e.g. single vs. multiple sessions) and what results might reasonably be expected. Pre-operative folliscopy will help to know the actual existing density of hair, so that postoperative results of newly transplanted hair grafts can be accurately assessed. Some patients may benefit with preoperative topical minoxidil application and vitamins.

For several days prior to surgery the patient refrains from using any medicines which might result in intraoperative bleeding and resultant poor grafting. Alcohol and smoking can contribute to poor graft survival. Post operative antibiotics are commonly prescribed to prevent wound or graft infections.

Harvesting methods
Transplant operations are performed on an outpatient basis, with mild sedation (optional) and injected local anesthesia. The scalp is shampooed and then treated with an antibacterial agent prior to the donor scalp being harvested.

There are several different techniques for harvesting hair follicles, each with their own advantages and disadvantages. Regardless of the harvesting technique, proper extraction of the hair follicle is paramount to ensure the viability of the transplanted hair and avoid transection, the cutting of the hair shaft from the hair follicle. Hair follicles grow at a slight angle to the skin’s surface, so transplanted tissue must be removed at a corresponding angle.

There are two main ways in which donor grafts are extracted today: strip excision harvesting, and follicular unit extraction.

Strip harvesting
Strip harvesting (also known as follicular unit transplantation or FUT) is the most common technique for removing hair and follicles from a donor site. The surgeon harvests a strip of skin from the posterior scalp, in an area of good hair growth. A single-, double-, or triple-bladed scalpel is used to remove strips of hair-bearing tissue from the donor site. Each incision is planned so that intact hair follicles are removed. The excised strip is about 1–1.5 x 15–30 cm in size. While closing the resulting wound, assistants begin to dissect individual follicular unit grafts, which are small, naturally formed groupings of hair follicles, from the strip. Working with binocular Stereo-microscopes, they carefully remove excess fibrous and fatty tissue while trying to avoid damage to the follicular cells that will be used for grafting. The latest method of closure is called ‘Trichophytic closure’ which results in much finer scars at the donor area.

The surgeon then uses very small micro blades or fine needles to puncture the sites for receiving the grafts, placing them in a predetermined density and pattern, and angling the wounds in a consistent fashion to promote a realistic hair pattern. The technicians generally do the final part of the procedure, inserting the individual grafts in place.

Strip harvesting will leave a thin linear scar in the donor area, which is typically covered by a patient’s hair even at relatively short lengths. The recovery period is around 2 weeks and will require the stitches/staples to be removed by medical personnel or sub cuticular suturing can be done.

Follicular unit extraction (FUE)
With Follicular Unit Extraction or FUE harvesting, individual follicular units containing 1 to 4 hairs are removed under local anesthesia; this micro removal typically uses tiny punches of between 0.6mm and 1.0mm in diameter. The surgeon then uses very small micro blades or fine needles to puncture the sites for receiving the grafts, placing them in a predetermined density and pattern, and angling the wounds in a consistent fashion to promote a realistic hair pattern. The technicians generally do the final part of the procedure, inserting the individual grafts in place.

FUE takes place in a single long session or multiple small sessions. The FUE procedure is more time-consuming than strip surgery. An FUE surgery time varies according to the surgeons experience, speed in harvesting and patient characteristics. The procedure can take anywhere from a couple hours to extract 200 grafts for a scar correction to a surgery over two consecutive days for a megasession of 2,500 to 3,000 grafts.With the FUE Hair Transplant procedure there are restrictions on patient candidacy.Clients are selected for FUE based on a fox test,though there is some debate about the usefulness of this in screening clients for FUE.

FUE can give very natural results. The advantage over strip harvesting is that FUE harvesting negates the need for large areas of scalp tissue to be harvested, so there is no linear incision on the back of the head and it doesn’t leave a linear scar. Because individual follicles are removed, only small, punctate scars remain which are virtually not visible and any post-surgical pain and discomfort is minimized. As no suture removal is required, recovery from Micro Grafting FUE is less than 7 days.

Disadvantages include increased surgical times and higher cost to the patient. It is challenging for new surgeons because the procedure is physically demanding and the learning curve to acquire the skills necessary is lengthy and tough.[citation needed] Some surgeons note that FUE can lead to a lower ratio of successfully transplanted follicles as compared to strip harvesting.

Follicular unit transplant
Follicular unit transplantation (FUT) is the traditional hair transplant method which involves extracting a linear strip of hair bearing skin from the back or the side of the scalp. The strip is then dissected to separate individual grafts.

Robotic hair restoration
Robotic hair restoration devices utilize cameras and robotic arms to assist the surgeon with the FUE procedure. In 2009, NeoGraft became the first robotic surgical device FDA approved for hair restoration.[8] The ARTAS System was FDA approved in 2011 for use in harvesting follicular units from brown-haired and black-haired men.

Types of surgery
There are a number of applications for hair transplant surgery, including:

Androgenetic alopecia
Eyebrow transplant
Frontal hair line lowering or reconstruction (naturally high hairlines without an existing hair loss condition)
If donor hair numbers from the back of the head are insufficient, it is possible to perform body hair transplantation (BHT) on appropriate candidates who have available donor hair on the chest, back, shoulders, torso and/or legs. Body hair transplant surgery can only be performed by the FUE harvesting method and, so, requires the skills of an experienced FUE surgeon. However, there are several factors for a potential BHT candidate to consider prior to surgery. These include understanding the natural difference in textural characteristics between body hair and scalp hair, growth rates, and having realistic expectations about the results of BHT surgery.

Post-operative care
Advances in wound care allow for semi-permeable dressing, which allow seepage of blood and tissue fluid, to be applied and changed at least daily. The vulnerable recipient area must be shielded from the sun, and shampooing is started two days after the surgery. Some surgeons will have the patient shampoo the day after surgery. Shampooing is important to prevent scabs from forming around the hair shaft. Scabs adhere to the hair shaft and increase the risk of losing newly transplanted hair follicles during the first 7 to 10 days post-op.

During the first ten days, some of the transplanted hairs, inevitably traumatized by their relocation, may fall out. This is referred to as “shock loss”. After two to three months new hair will begin to grow from the moved follicles. The patient’s hair will grow normally, and continue to thicken through the next six to nine months. Any subsequent hair loss is likely to be only from untreated areas. Some patients elect to use medications to retard such loss, while others plan a subsequent transplant procedure to deal with this eventuality.

Cost
The cost of hair transplantation depends on the individual hair loss and consequently on the number of necessary grafts. The average price per graft ranges between $1.07 USD in Turkey up to $7.00 USD in Canada. Some clinics also offer all-inclusive packages.