< Current issue
Dermatopathology: Practical & Conceptual April - June 1995
Searching for Diogenes: Bulge-Activation Hypothesis Part II—The Bulge is Not a Bulge
Cosimo Misciali, MD
A. Bernard Ackerman, MD
1927 Felix Pinkus
1951 Hermann Pinkus
1958 Hermann Pinkus
1961 Sanderson & Thiede
1987 Headington & Astle
1990 Leshin & White
1990 Cotsarelis, Sun, Lavker
1991 Sun, Cotsarelis, Lavker
1991 Lavker, Cotsarelis, Wei, Sun
1991 Lane, Wilson, Hughes, Leigh
1992 Jaworsky, Kligman, Murphy
1993 Yang, Lavker, Sun
1993 Lavker, Miller, Wilson, Costarelis, Wei, Yang, Sun
1993 Kobayashi, Rochat, Barrandon
1994 Rochat, Kobayashi, Barrandon
Beiträge zur Kenntnis des Haarwechsels bei menschlichen Embryonen und Neugeborenen. Morphol Arb. 1892;26:136-206 (
Fig. 4 [Fig. 11] General letter designation. AeW" Outer root sheath; G Glassy membrane; H Hair; HC Epithelial root cylinder; Hke Hair cone; HS Hair stem by Wertheim; ISA Insertion site of arrector; KS Germ layer; LfS Longitudinal fiber layer; MA Musculus arrector pili; Pg Pigment; Phm Papillary half-moon; Phs Papillary neck; PK Papillary button; PrR Productive region; RfS Circular fiber layer; RIW Rest of the internal root sheath; SS Spinous layer. Reproduced with permission.
The bulge is nothing more than the site of attachment of the hair arrector muscle.
The follicular cycle depends upon activation of the "productive region" of the outer sheath by a papilla contiguous with it.
The "productive region," a distinct zone positioned beneath the bulge, is the source of cells for downgrowth of epithelium that will become the new follicle.
For Garcia, the papilla was responsible for activating an anagen follicle, a key element of the bulge-activation hypothesis proposed a century later by Cotsarelis et al.
The drawing of follicles that appears in Garcia"s article shows that the "productive region" described by him corresponds to what today is considered to be the base of the isthmus. In short, Garcia depicts the base of the isthmus, rather than bulges of the isthmus, as the source of cells of a new follicle, an observation with which we concur.
This site is made possible in part by:
Copyright © Derm101.com. All Rights Reserved.