TIlE NATURE OF DANDRUFF 129 '•.•,.•.. •.!:•....- ..... .:.......: •'"'.:•'•..•-.:•::½" .............. :•:::.•... •..'%:•" •--id •- • -• •* ...• •.•:::•:::•:.:.• ......... .•?•-•:.'•.:.'.. •.::• ? ' '•: .•:L '.• .... ..:: ... -:,- .... •:-:- . -'• -....•-...: ............ •....:.•...... ........ ...• "•..•.,:•?('•-':•'::"*•:" --•:' Z•:-: •' •.• • ...... 1•:::: •:• ,'3. •:: •...d:" •.'•:,::• •:•:• :•': •.:.:., .•½?• ...... 2•'-.-:.,.-: ' "• •' . .-:-..- .... ..... ' : *'5-:•*e/:...½ •'":•'?' ....... ½. ( •::":." '%::• •": .' "-':•..:-• ..... :-' .... ... '5i•.""•"• .::•.""' --' 5. 24 '"=" ' :• :•, '"•" . - ' ...½ • ....%. •.:.- .....:.'.•.., .............. .... ..... .:. ................... '•. ........ •. %..• ........ .. , ..... • - '.•:•.," "•.:..::.:".%..•. •'• '.' •"" 7...:.. -, .:.:. ß .....'•. - -" :" •:':'"•%""' :'•:'..•'•::'•': 't'.':: '" '?'""":•'% 2:',?•'"?,'½•:--•""• ' ,: . .. -•' .' ..'.•. ............ ... '., ß .: .4 .. ' ..•..: • ß • :• -'.. •7• .... - ..... ß .............. .. . ,'•:...½•..:.....:::.:........ .:..•-:•........•:.: :•..,.•:: .: ...... ..' . , ..'...,..: .... :.'., % ..... .½ . •.- . •. . , • • .. .. •* •--.•.½,½• , ½.• .....•:.%..,.:%..._.,:.... ½•:: ß ::..• .•... .... ,•:.½... . ::....-'•-•' - •½•: :.. : .. , . . : - .•.• . -•. :' --...'•:•..::..:?"•:%" ' :•...'?:"•'.,•' .:•:4:,. '½ •::.'• '...'.:.:,•:,. •'.:..- d .,: . ß . - • •: •t, -- -• ': .... • , - •.. • • ..... ... -.,•....• ...... •,... • --:,.,. •--- ,...% .:.. , . % -- ,...- .¾-', •. •., -., •... ½.:. :... •......: . ,. - .. .. :.•. .. • :• , :- : . •. •- % • .... :::'?'?".. '..•$ •- .e" '- -7- ', ..?" :': % * .• '" -.• - '• .... •* .•7'• ':" .:&- -.,.S*c :'x: .' " --- . .. '-•, .' .'* '.,. *..., ..,• :...'$ •:.. . .•..'-- .:.S. *% .. Z.•-' ..-. .•. .. **- ,-...•½,'--•- -•::• '•'..,• 4:f- Figure 7. A parakeratotic scale (H&E, 620 x). Squaine has rnany nucleated cells. Large mm•ber of neutrophils has gathered below. Squames contain variable amount of dried up exudate, a crust Following the eloquent style of the French, he epitomized the sequence by the term "squirting capillaries." He envisioned that the capillaries squirted a load of serum and inflammatory cells into the epidermis, thereby creating mi- crovesicles full of neutrophils (Munro's abscesses). Squirting capallaries are also found in seborrheic dermatitis (12). Segments of parakeratosis are typical of both dermatoses, but are only one aspect of a much more complex abnor- mality. In danch'uff, they are superimposed on a normal background, little brushfires on an otherwise serene landscape. The size of an individual scale depends on the number of papillae involved. One squirting capillary produces a small scale, three adjacent ones a fairly good sized scale. It is rare for more than 3 contiguous papillae to be affected. The distribution of these inflammatory microloci is haphazard, though they seem to occur with higher h'equency next to hair follicles. We previously remarked that scales from dandruff and nondandruff could not be told apart. When individual sinall scales were lnechanically shaken so as to disperse the cells, we found that about one-third of the horny cells were nucleated. The percentage of nucleocytes was somewhat higher in larger scales, about 40 per cent. This concurs with the histologic impression of more intense inflammatory activity beneath the larger scales. By collecting scales and sectioning them en masse, one gains a different impression of how extensively these are permeated by neutrophils. Newly

130 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure at. Late stage of squame formation (H&E, 265 x). There is a small mound of para- keratotic cells. Underlying epidermis is normal and capillaries are quiescent foinned scales frequently show a solid mass of polys on their surface. The point here is that dandruff scales are heavily impregnated with inflammatory cells and serum and are actually "crusts." It is of more than passing interest that the biochemical changes in dandruff scales have a resemblance to psori- asis, as one might expect, since the dynamics are much the same. Subjects with severe dandruff often coinplain vociferously of scalp itching. Pruritus certainly occurs in nondandruff, also, but is less frequent and less distressing. Itching is, of course, highly variable and perceived differently by individuals. Tentatively, we consider itching to be set off by the squirting capillaries. Inflammatory microfoci in the papillae could readily activate fine sensory nerve fibers. We call particular attention to an artifact, which bewildered us for quite a while. This consisted of small loci of necrotic cells in the upper epidermis. These dead zones stained poorly, were shallow, and had a concave outline. We puzzled over them at length till we perceived that the horny layer over- lying them was ruptured. It finally occurred to us that the horny layer had