With the myriad of beautiful skin colors and tones the world over have you ever wondered how our skin gets its color and tone? The process by which the skin’s melanin behaves is both interesting and complex.
The discerning factor in many ethnic groups is skin color. The color of the skin is produced in the deepest layer of the epidermis—the basal layer—which houses not only the keratinocytes responsible for the progression of cells to produce the epidermis, but also the melanocytes responsible for the production of melanin. Melanin plays a key role in protecting the skin from the penetration of UV rays. The darker the skin, the less UV penetration and the lower the incidence of skin cancer. The number of pigment-producing cells, called melanocytes, is equal, no matter what the skin color. The difference is the structure and function of these cells.
To produce melanin, there has to be two components: an enzyme—tyrosinase, and an amino acid—tyrosine. When these two components go through a conversion process called dopa, melanin is produced. In skin of color, there is increased tyrosinase activity, producing a more concentrated melanin content. The pigment granule’s size is the basis for skin color differences; the darker the skin, the larger the granule.
There are two distinct components of melanin. One is constitutive melanin, or pigmentation, and the other is facultative pigmentation. Constitutive pigmentation is the pigment that resides within the keratinocytes and is produced from the body’s own metabolism. Facultative pigmentation is introduced through external stimuli.
The melanocyte is a dendritic cell. The dendrites are tentaclelike projections that enable pigment cells to be deposited into the keratinocyte. These projections are longer in darker skin, enabling pigment granule dispersion into the upper layers of the epidermis.
Another unique difference in darker skin is that pigment granules—also known as melanosomes—are dispersed singularly over the nucleus of the keratinocyte. In Caucasian skin, the granules are considerably smaller and are released in clusters. Racially blended and lighter global skin colors disperse a combination of both single—and clusters of—pigment granules. The activity of a melanosome transfer generally takes place within the lower and upper spinosum layer. In some cases, the transferral is disseminated as pigment droppings into the dermis as a result of injury or trauma to the skin.
And what about how your skin reflects light? This turns out to be an interesting scientific issue as well. Another Skin Inc. article offers an explanation:
Reflection and refraction of light play a large role in the perception of overall skin tone. About 5% of the light that hits facial skin is reflected off the skin’s surface, while the other 95% penetrates it.5–9 It is this light reflection process that gives human skin its optical depth. The white light passing through skin’s transparent surface reflects off of collagen, which essentially acts as a mirror beneath the surface. As the light reflects back to the surface, it absorbs color from pigments such as melanin and blood within skin’s many layers. Colored light is then diffused softly by the surface, generating a luminous glow.
With aging, collagen becomes more like an antique mirror, and light passes through it, compromising the skin’s ability to reflect and refract light. Additionally, uneven distributions of melanin, or age spots, and hemoglobin, or dilated or broken blood vessels, in the skin can further impede or scatter light, contributing to a dull, less luminous complexion.
These explanations about how our skin gets its color and tone are also a great reminder about how complex our skin and its processes are. Never underestimate it!
Image from braintraining101.com