The hair follicle is the cellular structure embedded in the dermis where hair originates. It includes the hair shaft (the visible part), protective sheaths, a sebaceous gland for hydration, and an erector muscle that causes hairs to stand on end.
Think of it as the "vase" nurturing hair growth.
The bulb forms the base of the hair shaft, slightly bulbous and directly linked to the follicle. It's soft, typically white (visible when hair is pulled), and houses the matrix where keratinization occurs—the process assembling keratin cells that form the hair.
In essence, it's the hair's root.
Vellus hair, or down, is the finest hair type with minimal melanin, making it nearly invisible. It's common on the face, while thicker intermediate hairs cover forearms and legs, and terminal hairs appear in areas like the pubis and armpits.
Simply put, it's very fine, almost transparent hair.
Folliculitis is inflammation of the hair follicle, triggered by irritation, bacterial infection, ingrown hairs (too fine to pierce the skin), chemical reactions, or UV exposure. It can range from redness to painful boils.
Monitor it; seek medical advice if painful. Avoid touching or forcing the hair out to prevent scarring, infection, or abscesses.
In short: ingrown hairs, redness, or pimples signal folliculitis.
Expert insight courtesy of Véronique Planchon, Director of Training at Laurence Dumont.
