BODY CARE
repeats itself throughout life. Compared to hair from the scalp, axillary hair show a slower growth rate, a shorter anagen phase and a high telogen ratio, which helps to understand how they have different length and thickness. Gender and ethnicity also play important roles
to determine the characteristics of hair. Women’s axillary hair grow at a slower rate than men’s hair. Due to the similarities with scalp hair, the methods developed and commonly used for hair care products are usable to study the axillas. The photo-trichogram is the gold standard for the study of hairs. It has been used for fundamental research to explore the characteristics of human body hairs as a function of the skin sites, gender and ethnicity,7 as well as for clinical studies aimed at evaluating the efficacy of hair removal treatments. Briefly, a small skin area (a few cm2
) is first
shaved and a high-resolution digital photograph of the site is taken. Forty-eight or seventy-two hours later, a second photograph is taken over the same site. Computer-assisted analysis allows to compare the photographs taken at the two different times and to extract parameters such as the hair density, the growth rate, the proportions of hairs in the different phases, and the anagen- to-telogen ratio, a key indicator of the health of the hair cycle. The thickness of axillary hairs can also be investigated using photo-trichogram.
In vivo assessment of hyperpigmentation of the axilla Hyperpigmentation or darkening of the skin in the axillae is a common cosmetic concern.
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Figure 1: Example of mapping and 3D reconstructions of some features of the axillary skin obtained in one subject using the Antera 3D imaging system. Clockwise from the top left: visible light photography, map of haemoglobin distribution, map of melanin distribution, folds and pores
It is a common complaint among women of dark complexion. For example, in Asia, having a white skin, even on body locations not easily noticeable such as armpits, is extremely important. Several treatments can help lighten and even out skin tone. These include chemical peels and laser procedures, but topical skin
lightening products are more frequently used since they are highly likely to induce less irritation. The colour of the skin depends on the
amounts and localization of pigments (mostly melanin, haemoglobin and carotenoids), the interaction between the incident light and the
www.personalcaremagazine.com
April 2025 PERSONAL CARE
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