Structure and Dynamics of Hair and Skin

Structure and Dynamics of Hair and Skin

The life and death of the human hair is a tale of little interest to ordinary mortals. But to the electrologist, who often plays a principal part in this microscopic drama, knowledge of the hair’s life cycle is vital to success. As executioner, she must destroy those renegade hairs which mar the countryside with their prickly presence, and to do so she must fully understand the hidden mechanisms which aid and abet them. This chapter is intended as an over-all blueprint of the architecture and activity of hair with special attention to those features which concern the

electrologist.

Because our purpose is primarily practical, the theoretical content of this chapter will be limited to those aspects of hair growth which are of immediate importance to the electrologist. The chapter has been divided into two sections. The first section provides a bare background of theoretical information to equip the student for state board examinations and to give her a general understanding of the structure and function of the tegument (the skin and its appendages). The second section offers a technical analysis of the intricate structure of the hair follicle and the details of its development. This knowledge is important for an understanding of the theory of permanent hair removal. An appendix has been added to illustrate actual variations in follicle structures as they occur in the human skin.

SECTION ONE: GENERAL THEORY

 

Skin Structure

Skin is an elastic, flexible membrane covering some fourteen square feet on the average person. It is thinnest on the lips and eyelids, while on the much-used palms and soles, it is at its thickest. Friction and pressure tend to increase the thickness of skin and exposure toughens it. Cold contracts it; warmth relaxes it.

Function Of Skin

As the largest of the organs of the body, the skin is more than a mere covering. The following are the six primary functions of the skin:

  1. Heat regulation. To maintain the normal body temperatures of 98.6°, the skin ”sweats” by producing moisture through secretions of the sudoriferous glands. The evaporation of this moisture has a cooling effect on the body.

  1. Because of the oily particles in the epidermis the skin will absorb oily substances without admitting any water substances. Certain drugs may therefore be applied topically.

  1. The sebaceous glands excrete sebum, an oily substance which helps to maintain the skin in a healthy condition.

  1. The fat cells provide protection against hard blows to the body. The Malpighian layer (stratum Malpighi) protects against the harmful effects of light. The outer, horny layers form a protection against the invasion of bacteria, as well as the wear and tear of abrasion.

  1. By the process of perspiration, the sudoriferous glands secrete waste materials.

  1. Nerve endings in skin allow us to detect heat, cold, touch, pleasure, pressure, and pain.

Stratification Of Skin

The skin is stratified into many layers, but most anatomists have found it convenient to discuss it in terms of three major subdivisions. At the surface we find the epidermis, also referred to as the cuticle or ”scarf skin.” Next comes the dermis, also called the derma, cutis, corium or true skin. Finally, we encounter the deepest layer, the subcutis, which is often called the subcutaneous or adipose layer. Some anatomists regard the subcutis as a continuation of the dermis.

EPIDERMIS

The epidermis consists of stratified squamis epithelium which form the protective covering of the true skin; squamis meaning made up of flattened cells, epithelium meaning a cellular substance of skin. All such cells are produced by a process called mitosis whereby certain cells continually divide into halves which grow into full-size cells.

Physiologists are not unanimous in defining or distinguishing the layers within the epidermis, but it will suffice for our purpose to regard the epidermis as containing four principal layers:

  1. Stratum Corneum the horny outer layer which constantly sheds its dead cells.
  2. Stratum Lucidum-somewhat less horny than the corneum.
  3. Stratum Granulosum-a layer of cells containing granules.
  4. Stratum Malpighii-the layer containing the pigment which deter- mines the color of one’s skin. This layer has also been called the mucous layer or stratum mucosum.

According to Montagna, the stratum germinativum is a single layer of cells which underlies and is considered a part of the stratum malpighii. The germinative cells of this layer produce all the other cells of the epidermis through the process of simple cell division (mitosis). The cells which are thus produced at first become ”prickle cells,” which constitute the stratum spinosum, the upper portion of the stratum malpighii. The prickle cells are themselves known to be capable of mitotic activity, especially in the lower third of their stratum. This merely indicates that the activity and structure of epidermal cells alter gradually in their upward development, rather than abruptly. These cells become flattened and lose their moisture as they rise to the surface, thus becoming a part of each stratum in turn, until they finally slough off as horny cells of the stratum corneum.

DERMIS

The next major subdivision of the skin, the dermis, is the part that gives the skin its pliability, through the elasticity of its constituent fibers. The dermis is considered to contain two sub-layers:

  1. Papillary Layer-layer of small, conical elevations, called papillae, containing blood vessels and nerve fibers. The layers of the epidermis receive all their nourishment through this blood supply. Through the nerve fibers we gain our sense of touch. Thus, papillae are most numerous in the fingers and on the tongue, where our sense of touch is most acute.
  2. Reticular Layer-contains fat cells, blood vessels, lymphatics, nerves, sebaceous and sudoriferous glands, fibrous and elastic tissue. The follicles of medium depth hairs extend into this region.

SUBCUTIS

The subcutis contains no differentiated layers but consists primarily of bundles of connective tissue-large loose meshes, fat cells, blood, nerves, and lymph supply. The deep-seated hair follicles extend into this area. The hair, the nails, the sebaceous glands, and the sudoriferous glands are all considered appendages of the skin. Each plays a definite role in the function of the tegument. Nails obviously are protective. The function of hair has already been discussed in Chapter One.

Glands Of The Skin

Sudoriferous glands are tubular organs consisting of coiled gl9merulus (see fig. 4 ) from which extend an excretory duct which opens at the skin surface to form a pore. Sudoriferous glands are abundant over the entire body but are predominant in the armpits, on the forehead, the palms of hands and soles of feet. They perform two functions:

  1. They eliminate waste materials through perspiration.
  2. They control body temperature by the evaporation of perspiration. We secrete about one quart of perspiration every 24 hours, but this rate will be increased by high temperature and humidity, exercise, drugs, excitement, nausea, nervousness, pain, or disease.

Sebaceous glands are of particular interest to the electrologist because lanugo hairs always begin their growth in a lobe of the sebaceous gland. Much more will be said of these glands later; it suffices for now to give only a brief explanation of their function. These glands are in the dermis on every part of the body except the palms and the soles. They are most numerous in the face. Although sebaceous glands are the source of new hairs, they are not always associated with hair follicles for there exist many sebaceous glands which have not been stimulated to produce hairs, as, for example, those highly active glands in the regions along the sides of the nose. The activity of the sebaceous glands performs the following:

  1. They produce and excrete sebum (a fatty substance).
  2. They lubricate and therefore condition the scalp, skin and hair shaft.

Sebum is a semi-liquid substance which consists of a mixture of oil, water and such waste materials as dead epithelial cells, fatty acids, fats, and salts. Because these materials are a product of degeneration, they cannot be said to be ”secreted,” they are ”excreted.” A modified sebum is found in the ear in the form of wax.

The Pilosebaceous Unit

Hair follicles, which are the pore-like indentations of the skin from which hairs grow, are sometimes found alone, but they are usually found associated with one or more sebaceous glands. The glands are positioned around the upper portion of the follicle with ducts entering the follicle cavity high in the dermis. The follicles and the sebaceous glands taken together comprise the pilosebaceous system and each member of the system is referred to as a pilosebaceous unit. Associated with each pilo-sebaceous unit is another appendage to the hair follicle, the arrectorpilorum. This involuntary muscle is attached at an angle to the base of the follicle. The follicle itself usually approaches the surface at a slant, but when the arrector contracts, either from cold or fright, the follicle and hair are pulled up straight, causing the texture of the skin to take on the appearance of ”gooseflesh.” These muscles are especially well- developed in dogs and cats, whose hair will stand straight out in moments of stress. Much more will be said about the pilosebaceous units in the second section of this chapter.

Hair

Hairs are keratinized, dead structures which no physiological factors · are known to influence once they are formed. Keratin itself is a hard horny substance which resists digestion by pepsin (an enzyme) and is insoluble in H20, organic solvents, dilute acids and alkalis. Nearly all syntheses in the epidermis seem to be aimed at the production of keratin, which provides a protective toughness for the entire surface of the body. We can understand the nature of hair better, then, when we realize that the hair follicle is merely an ”indentation” of the epidermis, with the walls of the follicle forming a continuation of the cellular layer of the skin surface. The keratinizing process in the follicle is a specialized version of what goes on throughout the surface epidermis.

The root is that portion of the hair which lies in the follicle, whereas the portion above the surface is called the shaft. The enlarged base of the root is called the bulb, which surrounds a mass of loose connective tissue termed the dermal papilla. The papilla contains a blood supply and other elements essential for the growth of hair, but it is not a ”part” of the follicle; it is a separate organ which serves the follicle.

SECTION TWO: HISTOLOGY OF THE PILOSEBACEOUS UNIT

 

Histology is the branch of science dealing with the microscopic study of the structure of tissues. The histology of the follicle and associated organs has particular significance for the electrologist’s ultimate purpose- the destruction of those cells and tissues which are responsible for the ‘f. development of new follicles. We cannot ”permanently” remove hairs unless we permanently disable follicle tissue from reforming. This requires a thorough understanding of follicle structure and development.

Types Of Hair Structures

The structure of a hair is directly associated with its follicle structure. There are only two general classifications of hair, lanugo and terminal; all others may be regarded as stages of transition between these two.

Lanugo (or vellus) hairs are the soft, downy type found on the cheeks and elsewhere. They usually lack pigmentation and grow from a shallow depth, having emanated from a lobe of the sebaceous gland. Lanugo hairs do not become terminal hairs unless stimulated by the topical or systemic conditions described in Chapter One.

It is the extent to which the blood supply at the papilla has developed which determines the vigor with which a hair and its follicle will grow. Medical literature is rather vague as to whether lanugo hair emanates from a true papilla as does the terminal hair. Most authorities consider lanugo hair as an appendage of the sebaceous gland, receiving its structure and nourishment from the supply available to the sebaceous gland itself. Since it has a very slow growth rate, lanugo hair could have only a rudimentary papilla and matrix from which it develops. These, in turn, must receive their nourishment from the adjacent walls of the sebaceous gland lobes. The sebaceous lobe containing a lanugo hair if stimulated by the glandular system or by topical irritation, may grow downward and become the follicle of a terminal hair. This change-over may take place in gradual steps over a period of from a few months to several years. In the early stages of change this lanugo hair is termed an ”accelerated” lanugo hair. This means the hair is longer than its neighbors but has not attained the vigorous growth of a terminal hair and apparently has no bulb. If stimulation should cease, an accelerated Lanugo hair will grow no deeper. The replacement hair may even return to the original depth if a permanent papilla failed to develop during the period of stimulation.

When the accelerated lanugo hair begins to develop pigmentation and becomes darker, the root will be deeper than that of non-pigmented accelerated lanugo hair. At this point the bulb shows signs of formation, and with further glandular stimulus this accelerated lanugo hair will make the transition to a shallow terminal hair, having picked up a major blood supply in the dermis.

Lanugo hairs have a shedding and replacement cycle as do terminal hairs. Very little medical research has been reported on lanugo hair growth or replacement rates, but observation indicates they grow slowly, taking two to three months to reappear after tweezing or waxing, and

remain dormant six to eight months before shedding.

Terminal hairs are the deep-seated coarse hairs which grow from the scalp, underarms, pubic region and other parts of the body. As distinguished from lanugo hairs, they have a well-developed root and bulb, often growing from a follicle which extends into the subcutis. The terminal

 hair, as distinguished from the simple lanugo hair, is comprised of three concentric layers:

  1. Cuticle This is a single layer of imbricated cells (scales) which overlap like shingles leading toward the tip. These contain no pigment. The overlap of these projections interlocks with that of the inner root sheath, anchoring the hair in the follicle. The cuticle serves to confine and protect the cortex and gives the hair its elasticity.
  2. Cortex This layer constitutes the mass of most hairs, consists of elongated keratinized cells cemented together. If the hair is pigmented, the pigment (melanin granules) will appear in this layer.
  3. Medulla This center section is composed of large loosely-connected keratinized cells. The medulla may be continuous or discontinuous. It may vary within the same hair. These variations in continuity result in air spaces which determine the sheen and color tones of the hair by influencing the reflections of light.

Follicle Structure

The follicle, like the hair, is not a simple structure. It is an indentation of the tegument and, as such, is constructed of concentric layers similar to layers of the skin surface. The layers of the follicle, in theory, constitute a downward extension of the topmost subdivision of the skin, i.e., the epidermis (excluding the horny layer). The effect might be likened to an inverted nipple produced by pushing one’s finger into a soft balloon, except that in the actual follicle the general structure of the indentation is modified to produce a hair.

The specialized structure of the follicle can be likened to a miniature outfit worn by each properly clad hair when it goes out. Its follicular attire consists of two layers of ”garments,” the inner root sheath and the outer root sheath. Like most modern underclothing, the inner root sheath is snug and brief, a composite of several layers of tissue which hug the hair as far up as the sebaceous gland ducts. Over this, fits a full-length outer sheath, a clinging gown of epithelium cells, continuous with the Malpighian layer of the epidermis. These two root sheaths, the inner and the outer, constitute the follicle itself.

It takes more than a follicle, however, to properly outfit any self-respecting hair. A topcoat is also provided in the form of a connective tissue sheath which surrounds the follicle with a loosely-knit mesh of papillary cells, interlaced with nerves and capillaries. All three sheaths, we shall find, are necessary equipment for the ”coming out” of a hair.

INNER ROOT SHEATH

The inner root sheath encases the hair root in three distinct layers of cells: (1) The cuticle layer which interlocks with the cuticle of the hair. (2) Huxley’s layer, the thickest of the three, and (3) Henle’s layer. The cellular growth of the inner root sheath originates from the bottom of the follicle at the papilla as does the hair and both grow upward in unison. At the level of the sebaceous gland the inner root sheath is dissolved, reabsorbed, or dissipated in some unknown manner allowing the hair to continue to grow upward through the hair canal (that portion of the follicle cavity above the inner root sheath).

There are two distinct layers that are referred to as ”cuticle.” One is the cuticle layer of the hair and the other is the cuticle layer of the inner root sheath. Both layers are shingle-like, but the shingles or imbrications point up on the hair and point down on the inner root sheath and therefore lock together, holding the hair firmly in place.

OUTER ROOT SHEATH

Surrounding the inner root sheath is the outer root sheath which constitutes the follicle wall. The thickness of the outer root sheath is uneven causing the hair to be eccentric in the follicle. The outer

sheath does not grow upward with the hair but remains stationary. At the level of the sebaceous gland and above, the cellular structure of the outer sheath cannot be distinguished from that of the surface epidermis, which is why the follicle is referred to as an indentation of the epidermis. The cellular structure of this sheath contains large amounts of water-soluble animal starch (glycogen) and appears most spongy in the middle third of the follicle. (The electrologist’s currents makes use of the greater moisture present at this level.)

The outer sheath is a continuation of the mitotic layer of the epidermis, the stratum malpighi. This outer root sheath is the permanent source of the ”hair germ” cells, from which new follicles are constructed when stimulated to action by local enzymes or hormones. This important function will be discussed in greater detail when we take up the dynamics of hair growth.

At the upper part of the follicle where the outer sheath blends with the epidermis there is some mitotic action that causes a keratinized sur- face layer to be produced. This is sort of a horny build-up that collects around the hair at the follicle opening. Because it is constantly being built up and sloughed off, its presence often causes difficulty to the electrologist. It sometimes blocks the follicle opening so effectively that it makes the insertion of the needle almost impossible.

CONNECTIVE TISSUE SHEATH

Outside of the follicle is the connective tissue sheath, which surrounds not only the follicle but the sebaceous glands as well. This papillary tissue serves the same function for the follicle that its counterpart, the papillary layer of the dermis, does for the epidermis; it provides both nerve endings and blood supply. The connective tissue sheath represents a continuous extension of the papillary layer of the derma and includes the dermal papilla itself. The dermal papilla as we have mentioned, is the crucial source of sustenance for the entire follicle structure. To appreciate the way the dermal papilla cells and the hair germ cells interact, we must examine the life cycle of the follicle, in which old hairs are replaced by new ones.

Dynamics Of Hair Growth

We have observed that many hairs begin as lanugo hairs and by glandular stimulation grow deeper, developing a bulb which encases a life-supplying papilla. During this process the hair increases in coarseness, takes on pigmentation and assumes the structure of a terminal hair. This process, however, it is not the ordinary life cycle (shedding cycle) of any single hair. Much lanugo hair remains lanugo hair for the lifetime of the individual. The same is true of most other hairs. Each of these hairs- lanugo, intermediate and terminal-has its own cycle of exchange or shedding, by which new hairs of the same type replace the old.

The lifetime of a terminal hair varies greatly among the various areas of the body and will differ from person to person. Lashes and brows last the shortest, dropping off after a scant four or five months. Scalp hair, on the other hand, averages from two to four years, with some individual cases ranging to seven years. The average growth rate of hair is approximately one-half inch per month, but the rate varies according to the type. In man each follicle has its own independent cycle, so man does not undergo periods of shedding as do certain animals. From 25 to 50 scalp hairs are lost each day by shedding.

At a certain time in its cycle, for reasons not too clearly understood, a terminal hair will separate from its papilla and, over a period of days, rise to the middle of the follicle, while retaining its attachment to the follicle wall. In this stage is called a club hair. After the club hair has risen, that portion of the follicle below the hair apparently shrinks upward, forming an epithelial sac beneath the base of the hair. The club hair is capable of obtaining some sustenance from the follicle wall, for it continues to grow from its new situation, deriving its nutrition from the sub-papillary plexus of the skin. Nevertheless, the new location is not permanent, and the club hair continues to rise until it has reached a point just beneath the opening of the duct of the sebaceous gland. Here it can no longer be nourished by the vascular supply, and it eventually become disengaged from the follicle wall entirely. The loosened hair then either falls out or is brushed away.

There is general agreement that the lower half of the follicle, including the outer sheath, comes and goes with the cycle, whereas the upper half remains stable. When a hair has been shed the follicle has degenerated to half its normal length. Within a period of from 60 to 150 days a new follicle will be constructed and the cycle will have begun all over.

 

Stages Of Development

Histologists divide the growth cycle into three stages called anagen, catagen and telogen. Anagen is a period of active growth, beginning at the moment the inactive follicle ”comes to life,” and descends to the papilla. This stage ends when the dermal papilla ceases to nourish the hair, at which time the hair comes loose from the papilla. During catagen the lower half of the follicle degenerates and the cells undergo a ”retrograde morphogenic transformation,” which is a complete reversal of the growth process. Telogen is a period of rest following catagen, at which time all that remains below the upper half of the follicle is a collection of ”hair germ” cells from the outer root sheath and the dormant dermal papilla cells. These cells are the basic units from which all later follicles will grow and to which each will ultimately return.

ANAGEN

The first phase of each cycle involves a complete rebuilding of the lower half of the follicle. At the beginning of anagen the hair germ cells, which extend downward from the base of the remaining follicle structure in a solid column called the dermal cord, proceed to multiply by mitosis and grow in width and depth into the subjacent dermis. Meanwhile at the tip of the cord a rounded depression is formed, into which have gathered the basic dermal papilla cells. This structure continues in its downward direction, the cord giving rise to the growth of the entire follicle, while the papilla cells blossom into the life-giving papilla. The lower part of the cord develops into a bulb which encases the papilla.

 At a point before the follicle has reached its ultimate depth, the mitotic cells in the lower part of the bulb, called the matrix, begin their activity. Out of the matrix spring all of the growing elements of the hair. These cells move upward from the matrix differentiating into hair and inner sheath. Keretinization occurs in the upper part of the bulb, producing a keratinized cone which spearheads its way through the solid cord, forming the inner sheath. Another keratinized structure, the hair itself, follows the tip of the advancing sheath, and breaks through the apex of the sheath about two thirds of the way up the follicle entering the permanent upper follicle and proceeding out through the pore as a visible shaft of hair. Throughout this time the follicle has continued to grow downward into the dermis. Not until the hair has grown approximately half an inch beyond the surface does the follicle cease to expand downward.

Figure 11 illustrates the four basic regions of specialized activity in the growth of hair. Below the critical level is the matrix, all the cells of which are mitotically active. The new cells pass upward to the upper bulb, where they first increase in size and then become elongated. While the cells are in the upper bulb and for some short distance beyond, in the region of cell growth and differentiation, the cells proceed to differentiate into those elements which comprise the three-layer structure of mature hair. However, up to and through this region, the on-rushing structures are still ”soft.” The keratogenous zone applies the final touch to nature’s product, solidifying the structure with keratin. The completed hair structure emerges from this zone approximately one third of the distance from the bottom of the follicle as a solid, durable shaft.

CATAGEN

After a certain period of constant growth, the catagen stage begins. Apparently, the papilla suddenly separates and withdraws from the matrix. As it rises, the hair is still rooted somewhat in the follicle walls and continues to be sustained in its growth by whatever nourishment is available from this secondary source. However, the collapse of the papilla initiates a degeneration of the follicle structure, causing undifferentiated cells to move inward into the area of the lower follicle. These cells form the dermal cord. Meanwhile, as we have mentioned, the hair becomes detached and is either shed or remains dormant, its club root lodged in the upper half of the follicle.

The period of time in which a follicle is in catagen is extremely short. A very small percentage of the hairs on any given area are in the catagen stage. Frequently, a follicle goes through this stage so rapidly that the follicle has no time to collapse. In such cases a new hair begins to emerge from the base of the follicle before the club hair has been shed, with the result that two hairs are found emerging in tandem from the same follicle, one firmly anchored to the base of the follicle, the other lodged in the upper portion of the follicle.

TELOGEN

Upon completion of the catagen stage, the upper portion of the follicle usually rests until stimulated to begin a new cycle. This period of rest is the telogen stage. The length of time that the follicle rests, as was stated earlier, varies widely according to the type of hair and the nature of the individual. In some cases a follicle will not go through a telogen stage: it begins to form a new hair immediately.

The photographs in Figures 15 and 16 illustrate the difference in root structure between a terminal hair in anagen and a club hair in telogen after they have been tweezed. The normal terminal hair slips out with bulb and surrounding tissue intact; it has a shiny look about it. The club hair has lost all contact with the surrounding tissue, and exhibits a clean, dry root with little straggly anchors by which the hair had been attached to the follicle wall.

Growth Potential In The Pilosebaceous Unit

To the electrologist, the most significant phase of hair growth is the process by which the pilosebaceous unit can replace a degenerated lower follicle. Practicing electrologists are aware of the weed-like obstinacy of this hair germinating process; regrowth from insufficiently- treated follicles is a major occupational problem. It follows that no electrologist is equipped to eliminate hair permanently until she appreciates the degree of cellular destruction, she must induce to remove all sources of potential regrowth.

Unhappily for the electrologist, there has never been a thorough laboratory investigation of the effect of electrical action on the growth cycle of the follicle. Electrologists have traditionally relied on the theory that destruction of the (dermal) papilla is sufficient to eliminate future growth, but they have never been able to point to specific research on the subject. Moreover, a high regrowth rate from certain electrical technics (principally flash thermolysis), offers persuasive evidence that exclusive destruction of the papilla is insufficient for eliminating the follicle permanently. Factors other than the existing papilla appear to be involved. Because of the lack of direct research on the subject, only a careful analysis of follicle histology can help us to discover the factors which cause regrowth from insufficiently treated follicles.

Authorities are in general agreement that two distinct structures are necessary to support the growth of hair, the follicle, and the papilla. During anagen, the papilla is identifiable as the connective tissue element enclosed by the mitotically active hair bulb; the papilla provides the nutriments for growth, while the follicle uses these nutriments to generate the hair. Obviously, if the papilla is damaged or destroyed during this phase of growth, the cycle will be interrupted, the hair will loosen from the follicle bottom, and the existing follicle itself, now lacking its source of sustenance, will wither away as it does in the catagen stage. Whether or not a new follicle will eventually develop is the object of our inquiry.

Let us examine the mechanics of the growth process more closely. In the normal stage of telogen the papilla persists as a compact ball of inactive dermal cells which have risen during catagen to a position which will vary in distance from the upper follicle according to local conditions. The shrunken lower follicle, called at this stage the epithelial sac, maintains contact with the dermal papilla by means of the dermal cord. This slender strand of hair germ cells, the cord, acts in intimate partnership with the inert dermal papilla. So long as the dermal cord completely bridges the gap between the upper outer follicle sheath and the papilla, the hair germ cells, and the papilla cells will ”team up” to

build a new follicle structure when stimulated by local biochemical processes.

It has been discovered through research (Montagna) that if the con- tact between the dermal papilla and the hair germ cells has been lost, the ”partnership” is dissolved, and no new hair can be formed from the existing structures. It follows that if the electrologist were to destroy the papilla at this stage, the existing team of cells will have been broken up for good. This fact seems to substantiate the electrologist’s traditional claim that elimination of the papilla at any stage in the growth cycle- anagen, catagen or telogen-is sufficient to prevent a pilosebaceous unit from producing new hairs. Yet, there is the question of high regrowth to be considered. The only interpretation which electrologists have been able to offer is that regrowth is a sign of failure to destroy the existing papilla, either because of insufficient current or failure to insert accurately. Some electrologists even go so far as to blame the problem on ”distorted” follicles or multiple papillas (pili-multigemini), phenomena which are relatively rare.

To come to a realistic interpretation of regrowth from improperly treated follicles, we must take two important factors into consideration. One is the fact that ”regrowths” from insufficiently treated follicles usually appear only after a prolonged period of quiescence. The other is that they usually return in the form of fine hairs which require many weeks to darken and deepen into the original type of hair. These considerations do not jibe with the fact that, normally, replacement hairs are immediately recognizable as similar to their predecessors. Instead, the new hair gives every evidence of having emanated from an entirely new follicle structure and papilla, beginning as if from a lobe of the sebaceous gland and deepening eventually into a mature structure. Thus, there appear to be two ways in which new follicles can be formed after a faulty treatment: (1) by regeneration of the undisturbed dermal cord and papilla (in a normal shedding cycle), and (2) by construction of a completely new lower follicle and papilla from those cells which remain intact after partial destruction of the cell structure. The latter is of great significance to the electrologist.

If our interpretation is correct, destruction of the existing papilla is not sufficient to frustrate the growth of new hairs from any given pilosebaceous unit. The hair germ cells themselves must also be eliminated. As research has revealed, the cells of the outer sheath in the upper part of the follicle comprise the permanent portion of the hair germ. These cells are known to possess a variety of potentialities. When sebaceous glands are destroyed, for instance, the cells readily produce new gland structures to replace those which were lost. There is no reason why these cells could not replace a lost follicle structure as well, after its papilla cells had been destroyed.

The crucial fact to be considered here is that most hairs treated by the electrologist are growing in follicles which originated through the catalytic action of androgenic hormones (Chapter I). Prior to the very first stirrings of hormone stimulation there were no existing papillas or dermal cords at the sites of these hairs- just hair germ cells in the area of the sebaceous glands and certain versatile cells capable of forming a papilla in the adjacent connective tissue sheath surrounding these glands. These were the potentials of the “team” of hair germ and papilla cells required to build a follicle, complete with papilla; it took only androgenic action to initiate their development.

The same conditions which originally brought about the hair that a patron wants removed are usually still present at the time of treatment. (The average patron possesses a high amount of androgenic hormones, and all of the team-building tissue. Therefore, if the electrologist destroys only the existing papilla, the ever-present hormones could easily stimulate a brand new team of cells into action, especially since injury to the area will have increased the local supply of life-giving blood. To produce a new follicle-building team the only parts of the follicle which need to survive are the upper outer root sheath and remnants of the connective tissue sheath which have remained intact. The resulting new hair would be exactly like the ”regrowth” we have been discussing; it would take a long time to appear and it would begin as a finer hair than the one it replaces, eventually accelerating to the depth of the former follicle.

The evidence seems to point to the conclusion that any pilosebaceous unit which still possesses hair germ cells and dermal cells has the potentials for renewing its function to produce hairs when stimulated by androgenic action. We therefore have good reason to believe that hair germ cells and dermal cells are just as vital a target for the electrologist as the existing dermal papilla.

Summary

The foregoing interpretations concerning the growth of hair were developed from recent writings on the normalgrowth of human hair. (See the bibliography at the back of this book.) To date there has been little research on the artificial interruption of the shedding cycle. We do not know, for example, exactly what happens when the electrologist’s needle introduces destructive currents into the follicle. The answer to this question is still a matter of theory-theory of little interest to anyone but the electrologist and for that reason largely unexplored.

In the absence of relevant research, the electrologist is best off adopting the most conservative theory-that is, the theory which holds that only the most thorough destruction can permanently eliminate regrowth.

The old-fashioned notion that only the papilla needs to be destroyed has been shown to be a gross oversimplification. It is known that a follicle is capable of more than one papilla. Even if the lower half of the follicle and the papilla are completely destroyed, the evidence indicates that an entirely new follicle can be constructed in its place.

It is evident that the electrologist must attempt to destroy the lower two-thirds of the follicle and a good portion of the connective tissue sheath to do an effective job. Only in this way can she be assured that she has eliminated all potentials for regrowth among existing hair germ and papillary cells. This fact will be of vital importance in our discussions of professional technics, to be taken up in the chapters on electrolysis, thermolysis and the blend.

APPENDIX: VARIATIONS IN FOLLICLE STRUCTURE

It is extremely difficult to envision the actual structure of pilosebaceous units simply from slides or drawings of them. However, Eugene J. Van Scott has developed an ingenious method for achieving an accurate ”picture” of follicle structures with a set of three-dimensional balsa wood models. In order to insure that the follicle models were perfectly proportioned, Scott used actual plugs of skin containing follicle clusters. These he sliced into microscopically thin layers, which were then placed on slides, stained, and photographed in order to obtain the organ’s measurements. Slices of balsa wood were then cut to match the follicle’s dimensions on a larger scale, so that when the slices were glued together, a magnified reproduction of the original pilosebaceous unit was formed. (You can see individual layers of wood if you inspect the photographs of the models carefully.) Arrows pointing from certain layers of the model to photomicrographs to the right of each illustration designate the actual section of tissue from which the balsa wood layer was shaped.

By examining and comparing the six pilosebaceous models presented below, the student can appreciate the variety of sizes, shapes and combinations in which these organs grow. All models were constructed with identical magnification so that the photographs which follow show the actual differences in their size. Sebaceous glands have been painted white to aid identification. Unfortunately, no dermal cords could be shown. The student must keep in mind that the true angle of the epidermis in relation to the surface of the epidermis has been ignored for ease of illustration. The follicle is very seldom perpendicular with the skin surface. In most instances it will be at an angle half-way between

horizontal and vertical (45°).

Figure 18 is a cluster of three pilosebaceous units from the scalp of an adult man. The deep follicle is active and growing and therefore is in anagen. The short follicle to the left is in telogen. It contains a club hair which is indicated by the letter ”C” on the tissue section pointed to by the arrow. The middle unit of this cluster contains no hair but for some reason is now merely a duct for the sebaceous gland.

This situation could result from the destruction of the lower half of the follicle by electrology. All three of these units share a common opening at the surface.

Figure 19 shows two hairs sharing the same hair canal, one growing (anagen) and one resting (telogen). Since both hairs reach the surface through a common opening there will be times when two hairs appear together in the opening. In a case such as this, an electrologist might mistakenly insert a needle into one follicle when the hair she wants to epilate is growing from the other follicle.

Figure 20 is a group of four follicles reaching the surface through one hair canal or opening. Three follicles are actively growing (anagen) while the one at the left rear, partially obscured from view, is resting (telogen). The follicle to the right has no sebaceous gland, but this is not uncommon.

Figure 21 shows two telogen hairs sharing one hair canal and surface opening. On either side of the resting terminal hair follicles are some lanugo hairs growing from their respective sebaceous gland openings.

Figure 22 shows two active follicles from a 7 year old girl’s back. Since these reproductions are

all to scale you can see the shallowness of these follicles in comparison with the depth of the others shown.

Figure 23 is the follicle of a beard hair of an adult male. Compare the width of the lower portion of this follicle with the follicle from a man’s back shown in Figure 19.

Although no balsa wood model has shown it, another hair structure should be considered in this appendix. On occasion one will find two active hairs emerging from the very same follicle. This phenomenon is called pili-multigemini. Pili-multigemini are proof that a follicle can posses.s more than one papilla, since each hair is an autonomous unit, with its own bulb and root structure. Figure 24 shows how two papillas share the same follicle. Each hair root has its own inner sheath while one outer sheath surrounds them both.