THE SOCIETY OF COSMETIC CHEMISTS
DISCUSSION
From the preceding studies a tentative conception of the nature of
dandruff has been formulated. It is proposed that profuse scaling of the
scalp, the hallmark of dandruff, represents a fundamental alteration in
the rate regulating mechanism of horny cell production, i.e., epidermal
turnover is increased. The rapid transit of cells to the surface does not
allow time for complete keratinization. This is betrayed by the presence
of parakeratotic cells. Horny layer coherence is affected and cracks
occur deep in the horny layer, producing large flakes. The intensified
scaling reflects both a true increase in the production of horny cells and
their beingr enderedm ore conspicuoubsy "crackingu p" and desquamating
as large aggregates.
In dandruff, unlike other conditions in which there is an increased
turnover rate of the epidermis, there is no histologic evidence of an
antecedent inflammatory stimulus to power the process. Nor is there
any other characteristic histologic change in the living part of the skin.
The principal pathology is located in the horny layer. The dead horny
layer cellsm ust reflectc hangesth at occurredw hent hey were living and
madet heir upwardm igration. Thesea berrationsi n the living epidermis
and perhaps the dermis are recondite and will require the more powerful
tools of electronmicroscopya nd biochemistry to define them. McOsker
and Hannon (5), in their electronm icroscopisct udiesd, id shows triking
alterations in the stratum corneum, but not in the viable epidermis.
It is therefore postulated that changes in the dandruff horny layer,
the chaotic pattern, "cracking up" into large cellular aggregates, crevices,
and sporadic parakeratosis, are secondary to more rapid epidermopoiesis
and perhaps some subtle change in epidermal physiology.
Whenever the rate of keratinization is acceleratedt, here is faulty cohesion
and evidence of incomplete keratinization. In terms of epidermal
kinetics, dandruff is perhaps intermediate between normal skin and
frankly pathologicc onditionss ucha s seborrheicd ermatitis and psoriasis.
If the structural and chemical changes characteristic of dandruff are
subsequentt o increasede pidermopoiesiso, ne might anticipate that the
biochemical changes in the dandruff horny layer would correspond to
those in psoriasis but to a far lesser extent. Preliminary data suggest
that these changes do occur in a diminutive way (15, 16). Dandruff
scales contain a high sulfhydryl and