1892 Garcia

 
Beiträge zur Kenntnis des Haarwechsels bei menschlichen Embryonen und Neugeborenen. Morphol Arb. 1892;26:136-206 (Fig. 4).

View Figure  		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.
 

Message

 
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.
 

Critique

 
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.