Exposure to Gamma-Rays at the Telogen Phase of the Hair Cycle Inhibits Hair Follicle Regeneration at the Anagen Phase in Mice

In 2014, Kimihiko Sugaya and Tomohisa Hirobe conducted a study on 115 mice to examine the effects of gamma-rays on hair follicle regeneration. They found that exposure to gamma-rays during the telogen (resting) phase of the hair cycle led to decreased hair follicle density and the induction of curved hair follicles in the subsequent anagen (growth) phase. This was accompanied by pigmentation anomalies, such as white hair and hypopigmented hair bulbs. These effects were dose-dependent, with even a relatively low dose of 0.5 Gy of gamma-rays affecting hair follicle regeneration. The study concluded that gamma-rays damage stem cells and progenitors for keratinocytes and melanocytes, thereby affecting the structure and character of regenerated hair follicles.