Determinants of Rate and Kinetics of Cell Division in Scalp Hair.

Mitotic activity of the germinative cell population comprising the hair matrix ranks among the highest known in mammalian tissues. In the mouse, for example, it has been estimated by Bullough and Laurence (1) that these cells may reduplicate their numbers in a period as short as 13 hours. Mitotic activity in hair roots of man is known to be high, but more definitive measurements of this have not been worked out. In previous studies it has been demonstrated that in the human hair root specific size relationships exist between the volume of hair matrix: volume of papilla, and number of mitoses in the matrix: number of cells in the papilla (2). The present paper details the mitotic pattern in the hair matrix of man and relates this pattern to possible determinants in the hair papilla.