The human hair: from anatomy to physiology

Abstract

This review could be the basis for improvement and progression in the field of hair research.

Anatomy and Physiology of Hair

“…Hair follicle density is much more condense in the forehead and follicular infundibular volume is also bigger. It is important just because of the large follicular infundibular volume that is associated with more follicular reservoir ability [1,13].…”

“…The upper follicle remains constant, while the lower part has continuous cycles of regeneration [1,2,16,18].…”

“…The upper part named acroinfundibulum, the keratinization of epithelium turns into the "epidermal mode", with formation of stratum granulosum and stratum corneum like a similar manner to epidermis [1,14,16].…”

“…In some follicles, there is a distinct single cell layer interposed between the outer and inner root sheaths, known as the companion layer [23]. Companion layer cells show numerous intercellular connections to the inner root sheath and are thought to migrated distally along with the inner root sheath to the isthmus region and to form the plane of slippage between the inner and outer root sheaths [1,3,14,16]. The ORS of the hair follicle also contains melanocytes, Langerhans cells and Merkel cells.…”

“…In humans, hair has various functions such as protection against external factors, sebum, apocrine sweat and pheromones production and thermoregulation. The hair also plays important roles for the individual's social and sexual interaction [1,2].…”