[Cell kinetic study in generating hair tissues in using anti-bromodeoxyuridine monoclonal antibody]

To determine the cell kinetics in generating and anagen hair tissues, cells in S-phase in the back skin of either newborn or 7-day-old mice were labeled with bromodeoxyuridine (BrdU) and stained immunohistologically using anti-BrdU monoclonal antibody (MoAb). In anagen hair tissues, a substantial number of cells in the hair bulb were stained. At suprabulbar portion, the outer root sheath (ORS) abruptly increased its thickness; in this area, many positive ORS cells were seen not only in the outermost cell layer but also in inner cell layers. However, the innermost cell layer of the ORS was negative. At the more distal portion of ORS, positive cells decreased in number and were located only in the outermost cell layer. In primary hair germ, lower outer cells were positive. In hair peg, these positive cells were separated into lower and upper groups. In the bulbous hair peg, the latter positive cells were located at the suprapapillary area, whereas the former group positive cells were in the outer part of the hair tissues. The suprapapillary group might be responsible for the production of hair cortex through the innermost cell layer of the ORS and the outer part group might be important for elongation of the hair tissue.