The growth of human hair occurs everywhere on the external body except for the soles of the feet, the palms of the hands, the lips, the backs of the ears, some external genital areas, the navel, and, apart from eyelashes, the eyelids.[1] Hair is a stratified squamous keratinized epithelium made of multi-layered flat cells whose rope-like filaments provide structure and strength to the hair shaft. The protein keratin makes up hair and stimulates hair growth. Hair follows a specific growth cycle with three distinct and concurrent phases: anagen, catagen, and telogen. Each phase has specific characteristics that determine the length of the hair.
HAIR GROWTH
Hair growth is defined as a coordinated process regulated by hormones that instruct hair follicles to produce new hair, which can vary in color and size during different hair cycles, influenced by age, development, and environmental changes.