1883 Unna

 
Entwicklungsgeschichte and Anatomie. In: Von Ziemssen H (ed). Handbuch der Speciellen Pathologie und Therapie. Leipzig: Verlag F.C.W. Vogel, 1883:1-114 (Fig. 3).

View Figure  		Fig. 3  [Fig. 12] D. "Bedded hair" that sends forth a new, productive epithelial projection; pe = productive epithelial projection; gp = papilla, which enlarges while it is pushed down; dstr = connective tissue strand, which becomes thickened and vascularized while the papilla descends, accompanied by prominent pigment formation. E. Initial "anlage" of the new hair; ph = primitive "germinal cone," which is cornified at the knoll and reveals puffed-up cells interiorly; a = a small artery that passes into the "hair strand"; dstr = markedly thickened old "hair strand", and out of its elements a lower region of the follicle is formed, again via the advancing epithelial projection. F. New cilium, still hidden beneath the "bedded hair"; ih = new cilium; bh = old "bedded hair"; hb = "hair bed," which again is well demarcated from the old "bedded hair" because the latter is loosened by the thrust of the new cilium. G.New cilium that after ejecting the old "bedded hair" grows freely in the old follicle, which tightens itself around the cilium; ho = cavity due to the loss of the knob-shaped end of the "bedded hair"; hb = epithelium of the wall of this cavity (the prior matrix of the "bedded hair"), which by proliferation gradually applies itself again to the new hair as a "spinous layer" of the middle region of the hair follicle; ih = new cilium. (Reproduced with permission.)
 

Message

 
In response to Schulin"s criticism, Unna argues against "the bulge" developing secondary to traction of the hair arrector muscle and for the importance of "the bulge" to conduction of the follicular cycle. He remarks that "the bulge" remains prominent even in follicles unassociated with a muscle of hair erection.
 
Unna illustrates by drawings the phases of the follicular cycle during which a bud of epithelium derived from "the bulge" gives rise to a new follicle.
 
Cone-like epithelial projections which Unna sometimes observed to emanate from "the bulge" are not normal, but pathologic.
 

Critique

 
Although Unna reaffirmed his hypothesis in regard to the relationship between "the bulge" and generation of a follicle anew, he did not offer compelling data in support of it.
 
Unna"s illustration of the follicular cycle depicts, correctly, anagen starting once a club hair has come to rest near the base of "the bulge."
 
Unna"s inference that some bulges are unassociated with muscles of hair erection resulted from an illusion created by the angle at which a histologic section has been cut. In actuality, bulges are attached consistently to follicles of smooth muscle.
 
The multiple cone-shaped projections of epithelium that Unna regarded as pathologic represent bulges of a follicle, and they are normal.