Human Fetal Hair Follicles: The Mesenchymal Component

Abstract

The factors that control the growth and development of hair follicles are largely unknown. Likewise little is known about why follicles periodically enter resting phases (telogen) and subsequently recenter an active growth phase (anagen). The dermal papilla of hair follicles probably influences follicular growth through the exact nature of this influence is obscure. To help delineate the role of dermal papillae in this regard, a series of hair follicles from 15 human embryos of various ages and from 2 human adults have been examined. The cells which form the dermal papillae were examined from the time they begin to congregate around the early hair peg to the point at which they reside within the follicular bulb. The plasma membranes of adjacent cells are attached by a focal types of intermediate junction. The junctions also connect the mesenchymal cells of the dermal papillae of human adult follicles. Cellular attachments of this type may have a similar function in regrowth or repair of adult tissue as they do in growth and development during embryogenesis.