Cell Proliferation During Fiber Growth Initiation in Ferret Hair Follicles

The study described the patterns of cell proliferation in ferret hair follicles during the initiation of autumn fur growth. Researchers synchronized the start of fur growth in 32 ferrets using melatonin implants and then collected skin samples over a period of 14 days to track the development of hair follicles. They used bromodeoxyuridine to label S-phase cells in vivo and an indirect immunocytochemical method to visualize proliferating cells in various parts of the hair follicle. They found no cell proliferation in telogen follicles until 4 days post-melatonin implant. The hair germ had the highest number of proliferating cells, which continued to be high at 14 days post-implant. In other tissues, cell proliferation peaked during mid to late proanagen and then declined as follicles reached the metanagen phase. The study concluded that critical signaling events for hair growth in ferrets occur between 0 and 4 days after melatonin implantation, highlighting distinct processes of follicular regeneration and fiber growth during the proanagen phase of the hair cycle.