How Does the Skin Make Color?
The pigment melanin is what gives our skin its color. While everyone has exactly the same number of melanocytes – the cells that produce melanin – the amount of melanin that each melanocyte makes can vary from person to person. Additionally, the size of the organelles where the melanin is housed can vary. These factors combine to influence the color of your skin.
What Is the Difference between Dark Skin and Light Skin?
Skin of color is darker than light skin by definition. What makes skin of color darker than light skin types?
- All skin colors have the same number of melanocytes. There are approximately 3,000 epidermal melanocytes in every square millimeter of skin.
- The difference in dark skin and light skin are the size of the melanosomes. Melanosomes are packets of color made by melanocytes. In white skin, melanosomes are small. In black skin, they are larger.
- The differences in pigmentation are also due to differences in the distribution of melanosomes within the keratinocytes. Keratinocytes are the main type of skin cell that are located within the epidermis. Those with darker skin have large melanosomes that are dispersed away from each other. Those with lighter skin have small, grouped melanosomes within keratinocytes.
The ONLY difference in white skin and dark skin is the size of the melanosomes and how they are dispersed in the skin cells (keratinocytes).
So how is melanin produced within the skin to create color? We can break the process down into three primary steps.
1. Melanin is produced.
Melanin is made using the pathway shown in the figure above. This process depends on an enzyme known as tyrosinase. When tyrosinase is blocked, the skin cannot make color. Many skin-lightening ingredients like hydroquinone, vitamin C, and kojic acid are aimed at blocking tyrosinase to treat and prevent dark spots on the skin.
The amount of melanin that your skin produces is not just influenced by genetics–external factors like sun exposure can also trigger excess melanin production, leading to dark spots and uneven skin tone.
2. Melanin is packaged inside melanosomes.
Once melanin is made, it is packaged into organelles called melanosomes. These melanosomes move up the “arms” of the melanocyte cell and pass through a “doorway“ into keratinocytes. This doorway is called PAR-2 or protease activated receptor 2.
3. Pigment stays in keratinocytes.
Once the melanin pigment reaches keratinocytes, it stays there until those cells exfoliate off of the skin’s surface and are replaced by new keratinocytes.
This is why exfoliating ingredients like alpha hydroxy acids (AHAs) can help to treat dark spots on the skin. AHAs like glycolic acid loosen the “glue” that holds keratinocytes together, causing older pigmented cells to shed off the surface of the skin.
The amount of melanin that your skin produces, the size of the melanosome “packages” that house the melanin, and the way that the melanin pigment is dispersed within skin cells all influence the outward color of your skin.
However, every human–regardless of skin color–has the same number of melanocyte cells that create melanin. Additionally, people of all skin tones can sustain sun damage, so daily sunscreen use is a must, no matter your skin color.
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