Dermatologica. 1987;175:19

Hair follicle biology and topical minoxidil
Headington JT.

The mechanism by which minoxidil stimulates hair growth remains undetermined. Possible indirect drug action, such as vasodilatation and increased blood flow to the dermal papilla, or possible local irritation related to minoxidil or to one or more components of the vehicle used for topical application has been suggested. Possible sites of direct drug action include either the dermal papilla of the follicle or hair matrix cells or possibly both. Because the dermal papilla of the hair follicle apparently controls both growth and differentiation of hair matrix cells and because there are no observable dysplastic or atypical changes in follicular germinal epithelium during or after application of topical minoxidil, it is concluded that the most probable site for the action of minoxidil is on the specialized mesenchymal cells of the follicular dermal papilla.