ROLE OF MACROPHAGES IN COLLAGEN RESORPTION DURING HAIR GROWTH CYCLE

During catagen, the cellular component of the connective tissue sheath consists exclusively of macrophages, which form a tightly packed layer around the hair follicle. These macrophages actively engulf and degrade the two layers of collagen fibers immediately surrounding the follicle. The cytoplasm of the macrophages contains engulfed collagen in various stages of degradation. Since hair growth is synchronous in mice, a substantial amount of collagen is degraded in the animal during catagen, which lasts only 2-3 days of each hair cycle. © 1969 Academic Press, Inc.