Microtubule Associated Protein 2 Expression Defines the Companion Layer of the Anagen Hair Follicle and an Analogous Zone in the Nail Unit

The study investigated the expression of Microtubule Associated Protein 2 (MAP-2) in the hair follicle and nail unit using immunohistochemical techniques on 25 scalp specimens and 3 nail specimens. MAP-2 was found almost exclusively in the companion layer of the anagen hair follicle, starting at the B-fringe and extending to the isthmus. This layer is characterized by unique cytoskeletal properties and its association with Henle's layer. The study suggested that MAP-2 is crucial for the structural integrity of the hair follicle, and disturbances in its expression could contribute to alopecia. Similar MAP-2 expression was observed in the upper layers of the nail matrix, indicating a potential analogous role in nail structure.