In this section you will review the anatomy and physiology of the hair and hair follicle and establish the contraindications for electrolysis treatments. In the third step you will look in detail at the consultation process. There are four steps to confirming the treatment plan:
Step 1 Hair facts for electrolysis
Step 2 Identify contraindications
Step 3 Consult with client
Step 4 The benefits and disadvantages of electrolysis
Step 1 Hair facts for electrolysis
In order to understand the way in which electrolysis works, and to select suitable candidates for treatment you need to understand in some depth the histology of the hair follicle and surrounding tissues, how hair grows and how it reacts to different types of hair removal. Hair is a sensitive, tactile organ which is capable of increasing awareness through sensation and touch. It grows at an angle to the surface, so that it follows the natural contours of the body above the surface. Let’s look at the types of hair first.
There are three different types of hair found on the human body: lanugo, vellus and terminal.
Lanugo hair is formed on the foetus whilst in the womb, usually shed around the seventh or eight month, but can be shed after birth. Hair that is being lost from the scalp due to baldness reverts to this primary type before disappearance. This hair is fine and soft without a medulla and usually unpigmented. Lanugo may reappear under conditions of starvation, for example, in someone suf fering from anorexia.
Vellus is fine soft hair which covers most of the body, except the palms, soles, lips and genital areas. This type of hair is non-pigmented, fine, downy and soft. It has no medulla, and has a shal low follicle, small blood supply and is usually less than 2cm in length and under 30µm in cross sectional diameter.
Terminal hair is longer, pigmented, varies in shape and usually exceeds 40µm in cross-sectional diameter. It is this hair that both men and women sometimes find superfluous and seek a means of having it removed.
Superfluous hair is a general term used to describe any unwanted hair and is what clients seek to have removed through temporary or permanent hair reduction treatments.
There are two types of terminal hair:
Structural and Cellular Features of a Hair Follicle
Secondly, let’s look at the structure of a typical terminal hair and the unit that contains it – the hair sheath and associated structures. Together they are called the pilosebaceous unit.
The pilosebaceous unit (pilo = hair, sebum = grease) consists of the hair follicle (the hair sheath and the hair), and the oil-producing or sebaceous gland. The sebaceous gland produces sebum, an oily compound that lubricates our skin and hair. The gland discharges the sebum through the pilosebaceous duct into the upper part of the hair follicle. In the axilla and the perineum or ano genital area apocrine glands are also associated with the pilosebaceous unit. The external auditory canal (ear canal) and areola (nipple area) of mammary skin contains apocrine glands in more limited numbers and they are rarely activated at these sites. Apocrine glands develop from and are associated with the hair follicles and their ducts open into the upper portion of the hair shaft. These glands produce sweat.
The pilo-sebaceous unit also contains a bundle of smooth muscle extending from the epidermis to the hair follicle. This muscle is called the arrector pili muscle and when it contracts it pulls the hair from its normal position lying at an angle to the skin into a vertical position. The muscle contracts in response to cold or fright. In fright the upright hair makes us look larger and thus more frightening – not unlike a cat’s tail when it is alarmed. In cold it is what causes “goose bumps”. This is an attempt to retain body heat by providing us with a thicker layer of “fur” – no longer much use in humans as our hair cover is minimal.
The hair follicle can be divided into three parts:
The inferior segment includes the deepest part of the hair follicle and extends to the bulge (the part just below the arrector pili muscle attachment). It contains the hair bulb or matrix with its ger minative matrix cells and melanocytes. The hair bulb surrounds a highly vascularised connective tissue called the dermal papilla. The cells in the matrix divide and form the hair. The cells divide
rapidly – about every 23 to 72 hours. This is one of the fastest division rates in the body. The isthmus extends from the bulge to the opening of the sebaceous duct.
The infundibulum extends from the sebaceous duct opening to the epidermal surface. Note: as the hair follicle is angled the bulge lies on the deeper aspect of the follicle.
The hair follicle is composed of the external and internal root sheaths and the hair shaft. When looking at a vertical section of the hair follicle it will display an external sheath, an internal sheath and a hair shaft.
The external sheath is formed by the basal and spinosum layers of the epidermis creating a downward structure. Towards the top of sheath, all the epidermal layers are present, whereas towards the bottom of the sheath, only the stratum basal is present. At the level of the infundibu-lum this external sheath is continuous with the epidermis. This layer never totally regresses and gives rise to the new hair in the next growth cycle. It contains melanocytes, Langerhan cells, mast cells, Merkel cells and neuronal stem cells. All these cells operate within the hair follicle and form a reservoir from which the epidermis regenerates after injury.
The internal sheath provides rigid support for the growing hair shaft. It tapers off above the bulge and does not grow beyond this level. The growing hair is shaped and curved by the internal sheath – this is the part that determines the shape of the hair.
The hair shaft is the part of the hair that we can see growing above the skin and which reaches down into the hair sheath. There are three main parts to the terminal hair shaft – the medulla, the cortex and the cuticle.
The medulla is the innermost part of the hair shaft when looking at a cross section. It is made up of rows of polyhedral cells. These contain eleiden (an early form of keratin) and air spaces. You will remember that eleiden is a component of the stratum lucidum in the epidermis. Eleiden is translu cent. The medulla may be absent in fine hair.
The cortex is the middle and major part of the hair. The cells in the cortex are elongated cells con taining melanin in dark hair. In white hair these cells contain air. This layer gives hair its colour.
The cuticle is the outermost layer of the hair and contains a single layer of thin flat cells which are keratinised. The arrangement of the cells is like that of shingles or fish scales with the edge of the cell pointing up. This layer protects the hair. The innermost layer of the internal sheath is also shingled and this helps keep the cuticle in place.
Try holding a single hair and moving fingers away from the scalp and then towards the scalp – you will notice a difference.