Histologic study of the regeneration of axillary hair after removal with subcutaneous tissue shaver

Abstract

It was observed that after subcutaneous tissue shaving for the radical therapy of hirsutism and hyperhidrosis axillary hair often regrew. Histologic study of this phenomenon showed that hair bulb and most of the follicle up to a level near the sebaceous duct opening had been removed. Hair regrows from remnant outer root sheath, but only when sebaceous glands are preserved, that is when the upper portion of the follicular isthmus is intact. One or several solid epithelial pegs grow downward from the cut end of the trichilemma, and inner root sheath and new young hair are formed in its center. In hair peg stage, the lower tip of the hair follicle descends while new hair is growing in its center through the mitotic activity of hair germ cells and is prevented from pushing toward the skin surface by interlocking fusion between hair cuticula and sheath cuticula. Eventually, the epithelial cells wrap around a mass of mesenchymal cells and form a new bulb from which the terminal hair grows upward. The new matrix acquires a new complement of functioning melanocytes.