Tm: .locitsst. or tsvss'riosrn's DERMATOLOGY. 62: 415-422. 1974
`
`
`
`
`
`
`
`
`
`
`
`’cupysgm © 1974 by The Williams a Wilkins Co.
`
`
`
`
`
`
`
`
`
`Vol. $2. No. 1!
`
`
`
`Prmted in l-'.S.A.
`
`
`
`
`
`
`
`
`
`
`
`
`
`REGIONAL DIFFERENCES [N THE THICKNESS (CELL LAYERS) OF THE HUMAN
`
`
`
`
`
`
`
`STRATUM CORNEUM: AN ULTRASTRUCTURAL ANALYSIS*
`KAREN A. HOLBROOK. PH.I).. AM) GEORGE F. UDI..-‘-\ND. MD.
`
`
`
`
`
`
`
`
`
`
`
`
`ABSTRACT
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`The importance of the stratum corneum as the rate-limiting barrier to percutaneous
`
`
`
`
`
`
`
`
`
`
`penetration has been well documented in the literature. Data have also been reported which
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`suggest that the barrier function of this zone varies among different regions of the body.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`However. little attention has been given to regional variation oi'two morphologic parameters
`
`
`
`
`
`
`
`
`
`
`
`
`
`known to affect permeability—thickness and number of cell layers. in the present study.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`significant regional variation in both the mean thickness and the mean number of cell layers
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`has been documented for four selected. sample regions of the body Ufa pflpulation of six adult
`
`
`
`
`
`
`
`
`
`
`
`
`volunteers. and for two more homogeneous subgroups separated by sex and age. While the
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`pooled data from the total population and the pooled data from the male and female
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`subgroups are in general agreement. it has been shown that there is also marked individual
`
`
`
`
`
`
`
`
`
`
`
`
`
`variation within a region that is characteristic and specific for each individual. The number
`
`
`
`
`
`
`
`
`
`
`of cell layers appears to account for the variation in thickness.
`
`
`
`
`
`
`1
`
`V
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`in the permeability of
`Widespread interest
`- human skin has generated a plethora of experimen-
`
`
`
`
`
`
`
`
`
`
`
`
`
`tal investigations using in vivo and in vitro tech-
`
`
`
`
`
`
`
`
`
`- niques. Several of the in vivo studies were carried
`
`
`
`
`
`
`out by measuring the diffusion of a radioactively
`
`
`
`
`
`
`
`
`“labeled compound through the epidermis and der-
`
`
`mis into the blood vascular system of living sub.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`'jects [1. 2]. Other investigators have used in vitro
`
`
`
`
`
`
`
`
`
`
`. model systems in their experimentation [3]. In the
`
`
`
`
`
`
`latter method. permeability of human cadaver skin
`
`
`. is measured. The measurements of the kinetics of
`
`
`
`
`
`
`
`
`
`
`
`
`transport that are obtained from both experimen-
`
`
`
`
`
`
`
`
`
`tal approaches would not be expected to differ
`
`
`
`
`
`significantly on the basis that only the nonviable
`
`
`
`
`
`”'cells of the stratum corneum serve as the rate-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`_ limiting barrier to the passage of substances across
`
`
`
`the epidermis [4 1.
`
`in part,
`The rate of diffusion of molecules is.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`dependent upon the length of the diffusion path-
`
`
`
`
`. way. which in this instance is the thickness ofthe
`
`
`
`
`
`stratum corneum. However. data on the thickness
`
`
`
`
`
`
`"of the stratum corneum are limited and general-
`
`
`
`
`
`
`
`ized and do not systematically take into account
`
`
`
`
`
`
`
`
`
`
`
`“the possibility of significant
`regional variations
`
`
`
`
`
`
`
`
`
`
`
`' which might be implied from the demonstration of
`
`
`
`
`
`
`regional variation in percutaneous absorption i1.
`
`
`. 2].
`The studies to investigate the differences in
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Hthickness and numbers of cell layers of the stratum
`
`
`
`
`
`
`
`comeum from different regions of the body have
`
`
`
`
`
`
`
`
`- failed to establish controls for preservation of the
`
`
`
`
`
`
`
`
`
`full thickness of the samples [5, 6]. Nonetheless.
`
`
`
`
`
`
`
`
`the importance of these two parameters of the
`
`
`
`
`
`
`.
`
`
`
`"
`
`This work was supported by USPHS Grants [ME-02600.
`
`
`
`
`
`
`
`
`AIM-08368. and (EM-16598 from the National Institutes of
`
`
`
`
`
`
`“Health. and by a grant from the Procter and Gamble
`
`
`
`
`
`
`
`
`
`Company. Cincinnati. Ohio.
`
`
`
`
`’ From the Department of Biological Structure [KAI-l
`
`
`
`
`
`
`
`
`
`and GFO). and the Department of Medicine. Division of
`
`
`
`
`
`
`
`
`
`. Dermatology tGFOJ. University of Washington School of
`
`
`
`
`
`
`
`
`
`Medicine. Seattle. Washington 93195.
`
`
`
`
`
`5
`
`u.
`
`V
`
`
`stratum corneum to the interpretation of permea-
`
`
`
`
`
`
`
`
`
`
`
`bility data has been recognized: "Strictly speak-
`
`
`
`
`
`
`
`ing. such comparisons of [rates of permeation] are
`not valid unless one corrects for horny layer thick~
`
`
`
`
`
`
`
`
`
`
`
`ness or alternatively for number of cell layers" [71.
`
`
`
`
`
`
`
`It was,
`therefore.
`the objective of the present
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`study to apply methods that would assure preser—
`vation of an intact. full-thickness stratum corneum
`
`
`
`
`
`
`
`
`and to evaluate quantitatively the regional varia-
`
`
`
`
`tion in total thickness and numbers of cell layers of
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`this epidermal zone using electron microscopy.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`MATERlALS AND METHODS
`
`
`
`i'lexor
`Specimens were obtained from the abdomen.
`
`
`
`
`
`
`forearm. anterior thigh. and posterior inferior iliac re—
`
`
`
`
`
`
`
`gion of six. healthy. human volunteer subjects.
`three
`
`
`
`
`
`
`
`
`white males and three white females within the age group
`
`
`
`
`
`
`
`
`
`
`
`of 25—31. The areas to be sampled were gently cleansed by
`
`
`
`
`
`
`
`
`
`
`
`a single stroke with a 70% alcohol wipe prior to biopsy
`
`
`
`
`
`
`
`
`
`
`with a high-speed. electric rotary drill fitted with a
`
`
`
`
`
`
`
`
`
`2.5-mm biopsy punch. The tissue "plug" obtained was
`
`
`
`
`
`
`
`
`then marked in a manner to assure the preservation of
`
`
`
`
`
`
`
`
`
`
`
`full-thickness stratum corneum during further process-
`
`
`
`
`
`ing. Small sheets of lens paper were placed above and
`
`
`
`
`
`
`
`
`
`below the core of tissue. The "sandwiched" preparation
`
`
`
`
`
`
`
`was then set onto a hollow plastic cylinder (prepared by
`
`
`
`
`
`
`
`
`trimming away the bottom of a BEEM capsule) and
`
`
`
`
`
`
`
`
`
`secured in place with an open-top cap iFig.
`Ii. The
`
`
`
`
`
`
`
`
`
`assembled capsule with the paper-enclosed biopsy sam-
`
`
`
`
`
`
`ple was carried through fixation, dehydration. and em-
`
`
`
`
`
`
`
`
`bedment for electron microscopy. Thus. cell layers which
`
`
`
`
`
`
`
`
`might have become detached during processing were
`
`
`
`
`
`
`
`trapped beneath the lens paper and could be included in
`
`
`
`
`
`
`
`
`
`
`the measurements of thickness and the counts of cell
`
`
`
`
`
`
`
`
`
`layers
`(Figs. 2a.bl.
`In pilot assays of
`this method.
`
`
`
`
`
`
`
`
`
`marking the surface with AgNO, and particulate carbon
`
`
`
`
`
`
`
`
`prior to removal of the biopsy specimen established that
`
`
`
`
`
`
`
`
`
`the technique of biopsying did not remove the outer layer
`
`
`
`
`
`
`
`
`
`
`of the stratum corneum.
`
`
`
`
`Tissue was fixed. for electron microscopy in 2 parts of
`
`
`
`
`
`
`
`
`
`
`
`'3‘“? osmium tetroxide buffered with 1 part of 0.2 M
`
`
`
`
`
`
`
`
`
`
`s-collidine at
`low temperature for 2 hr. dehydrated
`
`
`
`
`
`
`
`
`
`through a graded series of alcohols. and embedded in
`
`
`
`
`
`
`
`
`
`
`L'OREAL USA, INC. EX. 1017
`
`
`
`
`“31
`
`L'OREAL USA, INC. EX. 1017
`
`

`

`416
`
`
`THE JOURNAL OF INVESTIGATIVE DERMATOLOGE
`
`
`
`
`
`
`
`
`
`
`r'
`U —~ % - +
`Skin
`F.
`It“
`
`’
`biopsy
`.__L_,_.
`Lens paper
`
`
`markers
`
`
`Flush: nnq mm
`
`
`
`open lrd
`
`
`
`
`[he plashr
`[S]. Follnumg; pnlymrnzam-n.
`Epun '41.”
`
`
`
`
`
`
`r'yLindi-r Wm \‘H!
`tawny having the air-sue and enclming
`
`
`
`
`
`
`
`
`
`
`
`
`paper 11- hr urienled cm mL-Iui slum with the stratum
`
`
`
`
`
`
`
`
`
`
`t'nrm-um :‘mFiliUflE‘d parallel In rho tum ul' the mic-mumm-
`
`
`
`
`
`
`
`
`
`
`t'hm'k surh [hm tissue Hmflmm maulrl he cm in :I plmw
`
`
`
`
`
`
`
`
`
`
`
`perpendirularIn[ht-5kmsLJrl'.‘:t1-.'I‘l1u:k sections t 1.5 pm!
`
`
`
`
`
`
`
`
`
`were prepared with glass knm-s 21ml lhin sectinn». in Ihv
`
`
`
`
`
`
`
`
`
`‘llu-r mlr-rl'erenre color mnur. were ml through both thr-
`
`
`
`
`
`
`
`
`
`ll~4~ue and 1011: paper with :1 dmmund kniiv mounted un :1
`
`
`
`
`
`
`
`
`
`Ri-u'herl
`()m {.3 lillrmrm'rnn_>mc Several
`thin :zecliuns
`
`
`
`
`
`
`
`were ml at each 0! 8—41] uniformly separated intervals
`
`
`
`
`
`
`
`
`
`
`
`FIlOIIOn.
`dehydrmion ‘-
`and Wmfln
`Ior eleciron
`
`m'cmscm
`
`
`
`
`
`
`
`
`
`Assembled capsule.
`
`paper and biopsy
`
`
`
`
`
`
`I.”
`l
`ass-urt-
`in M. Huff
`[‘CLhmqur' ulemgnml
`[“1“
`
`
`
`
`
`
`
`
`
`
`prvsonatmn nf full-thickness sernlum mrneum during:
`
`
`
`
`[inner-5mm n! (Issue !ur elemrnn :nu'rusmpv.
`
`
`
`
`
`
`
`
`I
`
`
`
`LENB PAFEFI
`
`,;g x‘ *1.mi
`
`.../4%
`
`
`
`'..‘:
`Fm,
`;min-r marker uhuu-
`131 Light mn'rngraph shnwmu the lane-
`
`
`
`
`
`
`
`
`
`i
`‘lmi
`
`-
`Imcrngruph nt human epidermth and Ion.» paper marker
`r
`
`
`
`
`
`
`
`
`
`
`
`
`'nurmm epidermln I
`
`
`
`,
`
`"3|!-
`
`
`
`Ihl Eleclrun
`
`
`
`
`

`

`'I‘I-IIC‘KNESS 0F H’I‘RATI'M CORNEUM
`
`
`
`
`
`
`417
`
`
`
`
`
`
`
`
`
`
`
`
`[1 was estimmed Lhzn. measurements
`each skin sample.
`'Lhruugh the entire hinpsy sperimen. All sections were
`
`
`
`
`
`
`
`
`
`
`
`
`were made over a Inlal nl‘ 2072:”: lineal mm (if the stratum
`duuble stained with haturmed uram'l acetate and Hey,
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`ntild's 19]
`lead citrate. Sectinus were examined in a mrneum. For the purpose nI‘ex-aluming lhe thickness. :1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Philips 200 electrnu microscope.
`line was drawn through the straium mrueum perpenr
`
`
`
`
`
`
`
`
`
`
`
`
`Fifty electron mierngruphs were phntngraphed from
`ciirulnr 1n the skin surface nn ear-h micrograph and
`
`
`
`
`
`
`
`
`
`
`
`
`/
`
`
`
`.1
`
`r4
`
`..
`
`
`
`
`la. In Stratum eorneum from the posterior inferior iliac region. Note the variation in the ihickness along the
`FIG. 3:
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`- phmugrapheci segment. in,
`.- 3.865; 11,
`-: 4.050! lel Siralum mrueum From the thigh. The thickness is measured as the
`
`
`
`
`
`
`
`
`
`height of the black line and the. number of eells intersected are crammed.
`- 5,680]
`l
`
`
`
`
`
`
`
`
`
`
`
`y.
`
`
`
`
`
`

`

`
`418
`
`
`THE JOURNAL or INVESTIGATIVE oenmrocooi
`
`
`
`
`
`
`
`
`
`
`~
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`'4: Mean thickness and mean numbers of cell
`FIG.
`layers of the stratum corneum for the four regions saro—
`
`
`
`
`
`
`
`
`
`
`pied from six volunteer subjects. (Electron micrograph
`
`
`
`
`
`
`“figment;
`. 6.535!
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`.0001. The large standard deviations '
`level of 9 ~’
`
`
`
`
`calculated for these pooled data reflect
`two lea-
`
`
`
`
`
`
`turcs‘. til that
`the stratum ('nrneunt
`in a given
`
`
`
`
`
`
`
`
`
`
`
`sampled region is variable in both thickness and
`
`
`
`
`
`
`
`
`numbers of cell layers among [he subjects studied.
`
`
`
`
`
`
`and (2) that a sample length of stratum corneum'
`
`
`
`
`
`
`
`
`measured from any region of each individual is not
`
`
`
`
`
`
`
`
`
`consistent in thickness and numbers of cell layers.
`
`
`
`
`
`
`
`
`(Figs. :la.b_l. The individual data from each body
`
`
`
`
`
`
`
`
`
`
`
`
`region of each subject are expressed in Tables I
`
`
`
`
`
`
`
`(abdomen). [1 {flexor forearml. Ill lthight. and l\'
`
`
`
`
`
`
`(backl.
`
`the thickness of the
`it was also found that
`
`
`
`
`
`
`
`
`
`
`
`stratum corneum appears to vary proportionately
`
`
`
`
`
`
`
`
`
`
`
`
`
`with the numberof cell layers comprising that zone“
`
`
`
`
`
`of the epidermis. This proportionality has been
`
`
`
`
`
`
`
`
`
`calculated by dividing the mean thickness of each
`
`
`
`
`
`
`region by the mean number of cell layers for that
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`region. The resulting value also provides an averv
`
`
`-
`-
`'
`‘ .'
`'
`-
`
`
`
`
`
`
`
`age dimenston for 1ndtudual CE” thICknESb' 1r;
`
`
`
`
`
`
`
`
`three of the four regions the cell
`thickness was
`
`determined to be .l.‘—.18 um. However. by this»
`
`
`
`
`
`
`
`
`
`
`
`
`TABLE l
`measured from the deepest layers to the must superficial.
`
`
`
`
`
`
`
`
`
`The number of cells intersected by that line were then
`
`
`
`
`
`
`
`
`
`
`
`Mean. thickness (pm! and mean number of cell layers of
`
`
`
`
`
`
`
`
`
`
`cnunted (Fig. 3c). On several micrographs more than one
`
`
`
`
`
`
`
`
`
`the stratum comeum from the abdomen of six human
`
`
`
`
`
`
`
`
`
`measurement was obtained when the thickness of the
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` stratum corneum showed obvious variation along its subjects
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`photographed length tFigs. fiinJil.
`Fluff-“3%:
`
`
`
`
`
`
`
`
`
`The measurements were then type-d onto IBM com-
`7
`v '3'
`
`
`
`putt-r cards and submitted to the CDC 6400 computer for
`I
`i
`v "
`
`
`
`
`
`
`
`
`
`statistical analyses. Mean values. standard deviations.
`
`
`
`
`
`
`and p-valucs of comparisons were computed using ver-
`
`
`
`
`
`
`
`
`sion 2.1l ot’ the SPSS Statistical Package for the Social
`
`
`
`
`
`
`
`
`
`
`Sciences [In].
`
`
`
`
`
`
`r
`
`:
`Si
`¢
`i
`”It
`7“
`5
`
`‘3]
`;
`
`l /
`
`.‘L'l
`’-'
`
`,_..
`,
`
`l
`
`.
`
`l
`
`I
`l
`
`;
`i
`
`2
`
`n
`_ fl
`l
`l _ I
`‘
`l
`.
`'
`‘
`g”
`
`’ g
`l
`s " :
`it" a
`
`t
`‘
`
`'*
`
`l
`i
`
`
`
`‘
`
`
`
`_
`
`
`
`RESULTS
`
`
`
`
`
`
`
`
`
`
`
`
`It was the primary objective of this study to
`
`
`
`
`
`
`
`
`document regional variation in the thickness and
`
`
`
`
`
`
`
`
`
`number of cell layers ot'the stratum comeurn. first
`
`
`
`
`
`
`
`for a selected sample population and then for two.
`..
`.
`.
`.
`.
`
`
`
`
`
`
`more homogeneous subgroups 0! Individuals Within
`that population. The criteria used to establish the
`
`
`
`
`
`
`
`
`
`
`latter groups Were sex and age. The three male
`
`
`
`
`
`
`
`
`
`
`
`subjects selected were of ages 25%? and the three
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`female SUleeClS were 30-31 years Of age. The
`
`
`
`
`
`
`
`
`
`consistency of the data from each region and each
`
`
`
`
`
`
`
`individual was also considered in the interpretn-
`
`
`
`
`
`Lion of results.
`
`TABLE ll
`
`
`Mean thickness (umland mean number of cell layers of
`
`
`
`
`
`
`
`
`
`
`the stratum. carneum from the llcxor forearm of six
`
`
`
`
`
`
`
`
`
`human subjects
`
`
`
`n
`u
`‘ 0'
`'
`._1:7—.-—— ——
`..
`_
`....
`,wl if"
`
`
`.
`
`.
`
`~ 7
`
`
`Pooled Data from All Subjects
`
`
`
`
`
`Figure. 4 is a graphic representatitm of the mean
`
`
`
`
`
`
`
`
`
`values for both thickness and numbers of cell
`
`
`
`
`
`
`
`
`
`
`
`
`layers of the stratum corneum from the [our body
`
`
`
`
`
`
`
`
`
`
`
`regions tested. Each bar represents a composite
`
`
`
`
`
`mean value that was obtained as an average value
`
`
`
`
`
`of the individual means of the data from the six
`
`
`
`
`
`
`
`
`
`
`subjects selected. With the mean value of the
`
`
`
`
`
`
`
`
`abdominal stratum corneum serving as the stan-
`
`
`
`
`
`
`
`
`
`dard for comparison. both thickness and numbers
`
`
`
`
`
`
`
`
`
`
`of cell
`layers from the l'lexor forearm. thigh. and
`
`
`
`
`back were compared by use of the t—test and were
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`found to be significantly different at a confidence
`
`

`

`THICKNESS 0F STRATUM cosNEt'M
`
`
`
`
`
`
`
`419
`
`
`
`V '
`
`
`
`
`
`
`
`method of calculation the cells of the abdomen
`
`
`
`
`
`
`
`were estimated to have a greater average thickness
`
`
`
`
`
`
`
`
`.22 pm. These results appear to support
`of
`a
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`generalization that regional variation in the thick-
`ness ot stratum corneum is related to the number
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`,ot'cell layers that comprise it within a given region:
`
`
`
`
`
`
`
`
`
`the data appear to lend less support to an alternate
`
`
`
`
`
`
`
`
`
`
`. explanation of the regional differences as a conse-
`
`
`
`
`
`
`
`quence of extensive variation in individual cell
`thickness. These cmtclusions. although drawn from
`
`
`
`
`
`
`
`
`
`
`
`mean values computed from the. total population
`
`
`
`
`
`
`of subjects. are borne out by the data that were
`
`
`
`
`
`
`
`
`
`
`
`
`
`«summarized independently for the male and fe-
`male subgroups.
`
`
`
`
`‘ Pooled Data from Male and Female Subgroups
`
`
`
`
`
`
`
`
`
`
`
`
`
`Figure :3 graphically displays the mean values for
`
`stratum corneum thickness and numbers of cell
`
`
`
`
`
`
`
`
`
`
`
`layers of all female subjects. The same data are
`
`
`
`illustrated for the male subjects in Figure 6.
`In
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`'both groups.
`the mean thickness of the stratum
`
`.4
`
`
`
`
`
`
`
`.
`
`
`
`TABLE [It
`
`
`Mean thickness turn I and mean number of cell layers of
`
`
`
`
`
`
`
`
`
`the stratum corneum from the rhino of six human
`
`
`
`
`
`
`
`
`
`subjects
`
`(Mnr n-
`.t
`4r.
`... .. w
`“ mm
`'
`
`.
`
`.-
`
`.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`—-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
` uu
`
`
`
`
`
`TfllflKmall''“ATUKCOINEIJI
`
`I‘IIV'I
`
`NIMSH
`
`
`
`Fin. 5'. Mean thickness and mean number of cell layers
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`of the stratum corneum for the four regions sampled from
`
`
`
`
`
`
`the male subgroup. [Electron micrograph segments s.
`
`
`
`
`
`6.35:?)
`
`
`
`
`1133II'0"
`
`
`
`
`
`THICKNESSo!I'I'M'I'IJICOIHEU‘DI
`
`{pl}
`
`
`
`IIJAV'I1113I“‘ou
`
`“noun:
`
`rum:
`router.)-
`
`rn IGB
`
`M“
`
`ti.- Mean thickness and mean number of cell
`Ftc.
`
`
`
`
`
`
`
`
`layers of the stratum corneum for the four regions sam-
`
`
`
`
`
`
`
`
`
`pled from the female subgroup.
`lElectron micrograph
`
`
`
`
`
`
`segments - 6.365)
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`.0001) when
`corneurn is significantly different tp <1
`
`
`
`
`
`
`
`
`compared with the mean abdominal dimensions.
`The mean numbers of cell layers were also signifi-
`
`
`
`
`
`
`
`
`
`
`
`cantly different [p <.
`.0001) among the four regions
`
`
`
`
`
`
`
`
`of the male subjects. but did not differ significantly
`
`
`
`
`
`
`
`
`
`
`
`.154]
`[1)
`in a comparison of the abdomen and
`7
`
`
`back of female subjects. It may be noted that the
`
`
`
`
`
`
`
`calculated individual cell thickness is greater for
`
`
`
`
`
`
`the female subjects as a group and for each female
`
`
`
`
`
`
`
`
`
`
`
`
`
`subject
`individually when Compared with the
`
`
`
`
`
`
`
`group of males and with the individual male
`
`
`
`
`subjects. Again. male and female group data
`
`
`indicate that there are thicker cells in the abdomi-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`nal region. The pooled data from the total popula»
`
`
`tion and the data from the two subgroups are in
`
`
`
`
`
`
`
`
`
`good agreement.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`. I!
`
`a
`
`.
`
`
`
`'
`r4
`
`
`lib
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`TABLE l\'
`
`
`Mean thickness turn) and mean number of cell layers of
`
`
`
`
`
`
`
`
`
`
`the stratum corneum from the back ofsix human subjects
`
`
`
`
`
`
`
`
`
`
`l
`14.10 Mam -t..,..t..t..,»."gtm
`.n—t 2.,
`,.
`w_
`v
`‘
`.
`h
`.
`r.
`.
`..
`r
`..
`4L
`'
`
`.‘
`
`v
`l
`
`
`
`
`
`
`
`

`

`
`420
`
`THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
`
`
`
`
`
`
`
`
`
`
`
`Individual Data
`
`
`
`It may be seen from Tables l—IV that there is
`
`
`
`
`
`
`
`
`
`
`
`
`
`significant variation among individuals in both
`
`
`
`
`
`
`
`thickness and numbers of cell layers of the stratum
`
`
`
`
`
`
`corneum from the regions sampled. Having estab~
`lished the individual variation. we then considered
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`whether it would be possible to obtain a value for
`
`
`
`
`
`
`
`
`
`each subject that could be used to “correct” the
`
`
`
`
`
`
`
`data for individual variation and obtain theoretical
`
`
`
`
`
`
`
`
`values for thickness and numbers-of- cell bursts that
`
`
`
`
`
`
`
`would be equivalent among subjects. The mean
`
`
`
`
`
`
`
`
`
`thickness and the mean number of cell layers from
`
`
`
`
`
`
`
`
`the abdomen. fiexor forearm. thigh, and back of
`
`
`
`
`
`
`
`
`each subject were averaged to obtain an overall
`
`
`
`
`
`
`
`
`“body value" for thickness and numbers of cell
`layers characteristic of each subject. These aver-
`
`
`
`
`
`
`ages were then used to obtain a mean value for
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`thickness and numbers of cell layers for the group
`of subjects. Deviation from this mean was calcu-
`
`
`
`
`
`
`
`lated for each subject and that value was used as a
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`factor to adjust the individual regional data. The
`
`
`
`
`
`
`
`
`
`
`results of this method to con-act
`the data only
`
`
`
`
`
`
`further emphasized and supported the conclusion
`
`
`
`
`
`
`
`of specific individual variation in a region among
`
`
`
`
`
`
`the subjects of a. population.
`
`
`
`
`DISCUSSION
`
`
`This study is the only work to date in which
`
`
`
`
`
`
`
`
`
`
`measurements of the thickness and numbers of cell
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`layers of the stratum corneum are compared from
`
`
`several body regions of the same subject. Blair [5]
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`has reported the mean number of horny cell layers
`
`
`
`
`
`
`
`
`and mean horny cell thickness characteristic of the
`
`
`
`
`
`
`interscapuler region and the extensor forearm. but
`
`
`
`
`
`
`
`
`the biopsies studied from these into regions appear
`
`
`
`
`
`
`
`to have been obtained from different subjects. The
`
`
`
`
`
`
`
`
`author’s primary concern was to adopt and elabo-
`
`
`
`
`
`
`
`
`rate a method to enhance visualization of horny
`
`
`
`
`
`
`
`
`
`cell layers and not to-compare the stratum corneum
`
`from the two regibns Baker and Kligm‘an [7]
`
`
`
`
`
`
`
`
`
`
`
`
`
`acknowledged regional variation in the stratum
`
`
`
`
`
`
`
`cornsum thickness and/or numbers of cell layers.
`but they used this information only to advocate
`
`
`
`
`
`
`
`
`care in interpretation of permeability data.
`In
`
`
`
`
`
`
`
`another study in which functional differences in
`
`
`
`
`
`
`
`the stratum corneum were compared. Smith.
`
`
`
`
`
`
`Fischer, and Blank ill] compared the numbers of
`
`
`
`
`
`
`
`
`layers of cells from the abdominal and scrotal
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`stratum corneum by repeatedly stripping this
`
`
`
`
`
`
`layer. Rushmer and co-workers
`reported
`[12]
`
`
`
`
`
`
`
`
`their findings on the total skin (epidermis plus
`dermis) thickness of the scalp.
`forehead, back.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`abdominal, thigh. wrist. and palmar surfaces and
`included light microscopic measurements of the
`
`
`
`
`
`
`stratum corneum from the flexor forearm. sole.
`
`
`
`
`
`
`
`scrotum. and callus.
`
`
`
`
`It is therefore apparent that while many authors
`
`
`
`
`
`
`
`have reported values of thickness and numbers of
`
`
`
`
`
`
`
`
`
`cell layers or the stratum corneum. their results
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`have been obtained by diverse methodology. Some
`of the techniques which have been used to estimate
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`both of these parameters include: (1) scotch tape
`
`
`
`
`
`
`
`
`stripping to remove the cell layers: the numbers of
`
`
`
`
`
`
`
`
`strippings were correlated with the numbers of cell
`layers [13];
`(2] treatment of paraffin-embedded-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`and frozen biopsies with alkali to cause swelling.
`hence better visualization and more accurate .
`
`
`
`
`
`
`
`
`
`
`
`counting of the horny cell layers [14]; (3} applica-
`
`
`
`
`
`
`
`
`
`
`tion of standard chemical fixation. paraffin em-
`
`
`
`
`
`
`bedment. and staining procedures for histologic
`sections: thickness was measured with a microme-
`
`
`
`
`
`
`ter eyepiece [15]; i4) mechanical measurement of
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`dried tisme by means of a modified Starett gauge
`
`
`
`
`
`
`
`IS]: and (5') preparation of tissue by chemical_
`
`fixation and plastic embedrnent for electron mi-
`
`
`
`
`
`
`
`croscopy: measurements were made from electron .
`
`
`
`
`
`
`
`
`
`
`
`
`micrograp'hs [16]. No techniques have been de-
`scribed in any of these studies to insure full
`
`
`
`
`
`
`
`
`thickness preservation of stratum corneum.
`
`
`
`
`
`
`
`
`
`
`r
`
`General Body Thickness of Human Stratum
`
`
`
`
`
`Comm
`
`The thickness of the stratum corneum has been .
`
`
`
`
`
`
`
`
`
`too frequently expressed in a single value
`all
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`intended to be representative of the body as a'
`
`
`
`
`
`
`
`
`whole. These figures are probably not a true
`
`
`
`
`
`
`average calculated from several body regions. but
`
`
`
`
`
`
`
`
`rather were based on on isolated measurement.
`
`
`
`Values of [3.2 pm [17]. H um [18]. and 15 pm [191‘
`
`
`
`
`
`have been reported as an average thickness of dry
`
`
`
`
`
`
`
`
`
`
`stratum corneum. By comparison. our “body aver-
`
`
`
`
`
`
`ages" calculated as the average value of the mean
`
`
`
`
`
`
`
`
`
`thicknesses of the four regions ranged from Bil—12.9
`
`
`
`
`
`
`
`
`
`
`1.1m. Only the flexor forearm. and in one case the
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`thigh. had a mean thickness within the range
`
`assumed as an average for the whole body by other
`
`
`
`
`
`
`
`
`
`authors.
`
`
`Again. without reference to regional variation. '
`
`
`
`
`
`
`
`
`
`
`
`
`
`the stratum comeum has been discussed as ap-
`
`
`
`
`
`
`
`
`proximately 15 cell
`layers thick except
`for the
`
`
`
`
`
`
`
`
`
`palm. sole. scrotum. hand. and foot
`[1-11 or has
`
`
`
`
`
`
`
`
`
`been described in ranges of 10-223 cell layers [20]
`
`
`
`
`
`
`
`
`
`
`and 15—30 cell layers with 20—22 most frequently
`
`
`
`
`
`
`
`
`
`counted [21]. In this parameter, our data for the
`
`
`
`
`
`
`
`
`
`mean numbers of cell
`layers of the. four regions”
`
`
`
`
`
`
`
`
`
`
`sampled lie within a more narrow range of 14—23311
`
`
`
`
`
`
`
`cells. Only one enceptional measurement. from the ‘
`
`
`
`
`
`
`
`
`
`flexor forearm. of 30 cells was counted. “Body
`
`
`
`
`
`
`
`
`averages" for the numbers of cell layers compared
`
`
`
`
`
`
`favorably (15.6—22.8) with the range expressed
`from the individual data.
`
`
`
`
`
`
`
`
`Regional Variation in the Stratum Corneum
`
`
`
`
`
`
`It has been commonly recognized but poorly
`
`
`
`
`
`documented that the thickness of the epidermis as
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`a whole [15. 12] and ot‘ the stratum corneum
`
`
`portion of the epidermis specifically. vary in thick-
`
`
`
`
`
`
`ness and numbers of cell layers in different regions
`
`
`
`
`
`
`
`
`
`of the body. We have selected four regions of thou
`
`
`
`
`
`
`
`
`
`
`body in document
`this variation. The data ob-
`
`
`
`
`
`
`
`
`tained in this study and the measurements which
`
`
`
`
`
`
`
`have been reported in the literature for the same
`
`
`
`
`
`
`
`
`regions are compared in Table V.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`Comparison of measurements of thickness and numbers of cell layers reported in the literature and measurements
`
`
`
`obtained in the present study
`
`
`
`
`
`
`
`“m“ if FT
`1”
`
`
`
`
`
`
`
`
`
`
`
`
`Abdomen
`13 um
`Scheuplein [18]
`V5725
`
`
`
`
`
`Blank ti: Scheupiein [2T]
`
`
`
`
`
`
`18
`
`‘ 18 mean
`
`
`* iii—20.9 range
`
`
`
`
`
`
`10.2-23.4
`25
`
`“21.6 mean
`
`
`‘16.7—l30 range
`
`
`
`
`
`
`No reported
`measurements
`
`
`
`‘193 mean
`
`
`'14.:1-‘22.‘l range
`
`
`
`
`
`9.64011
`
`
`
`14—28
`
`
`19 mean
`
`
`
`
`
`
`
`
`
`
`Brody [16]
`
`
`
`
`
`
`Smith. Fischer. 8; Blank
`l11 l
`
`
`
`
`
`
`Blair [5]
`Odland [28]
`
`
`
`
`
`Blair [5] {measurements
`
`obtained from interscap-
`
`
`ular region]
`
`
`
`Anderson 8: Cassidy [5]
`
`
`
`(measurements obtained
`
`from "hip")
`
`
`
`
`
`
`
`‘15)} mean
`“3.4 pm mean
`
`
`
`
`
`
`
`
`
`
`
`
`
`*8.2—11.3 range
`*14-21J range
`1
`“‘ Measurements obtained in the present study.
`
`
`
`
`
`
`
`THICKNESS DF STRATUM CDRNEUM
`
`
`
`
`
`
`421
`
`
`TABLE V
`
`
`
`
`
`‘ Flexor
`
`forearm
`
`
`
`Thigh
`
`
`
`"
`
`I Back
`
`
`
`
`
`
`
`
`40 pm
`
`
`'82 am mean
`
`
`‘fi.9—9.8 range
`
`
`
`
`15 pm
`
`
`
`‘12.!) um mean
`
`
`’8.l—.l6.2.um range
`
`
`
`
`
`8.57 13.8 um
`
`
`
`'10.B um mean
`
`
`*7 .77 15.3 range
`
`
`
`
`['2 pm
`
`
`
`6.2s19.l
`
`
`11.8 mean
`
`
`
`
`
`
`
`
`
`Rushmer e1 al [12]
`
`
`
`Humphries & Wildnauer
`['26] (measurements
`
`
`obtained on "leg"!
`
`
`
`
`
`
`Humphries 8: Wildnauer
`
`
`['26]
`
`
`
`
`Anderson & Cassidy [6]
`
`
`
`
`(measurements obtained
`
`from “hip"i
`
`
`
`
`
`'
`
`'
`
`I
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Number of cell layers. in the majority of exam—
`
`
`
`
`
`
`
`
`ples. our measurements for the number of cell
`
`
`
`
`
`
`
`
`layers comprising the stratum corneum in a given
`
`
`
`
`
`
`
`region compare favorably with the values reported
`in the literature. In those instances where there are
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`discrepancies. we may account for the differences
`
`
`
`
`
`
`
`
`
`
`by the failure of others to control the preservation
`
`
`
`
`of all layers in tissue processing.
`
`
`
`Thickness. There is considerably more variance
`
`
`
`
`between our measurements of thickness and those
`
`
`
`
`
`
`
`
`
`
`reported in the literature. Again, methods ol'tissue
`
`
`
`
`
`
`
`
`preservation may explain these discrepancies. The
`amount 01' water allowed to remain in the tissue
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`during processing can account for significant alter—
`ation in this measurement. The stratum corneum
`
`
`
`
`
`
`
`can increase its thickness severalfold when fully
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`‘ hydrated.
`Idson [22] has reported that. a dry
`
`
`stratum corneum of 15 ,um thickness can expand to
`
`
`
`
`
`
`
`
`
`
`
`
`48 pm when fully hydrated. It is. in fact. possible
`
`
`
`
`
`
`
`
`
`
`
`
`that processing of horny layer for microscopic
`
`
`
`
`
`
`analysis alters the thickness significantly.
`A further consideration when comparing the
`
`
`
`
`
`
`thickness and numbers of cell layers from several
`
`
`
`
`
`
`
`
`
`
`
`4 studies is the precise location ot'snmpling. Identifi-
`
`
`
`
`
`
`
`
`
`
`cation oi' the region investigated is usually limited
`
`
`
`
`
`
`
`
`
`
`to a general term such as back. abdomen, or thigh.
`
`
`
`
`
`Can we compare our “back" measurements from
`
`
`
`
`
`
`
`
`
`
`the posterior and inferior
`iliac region with less
`
`
`
`
`
`
`
`
`
`
`
`specifically indicated "hack" measurements of
`
`
`
`
`
`
`
`other investigators? One might expect there to be
`
`
`
`
`
`significant regional variation within any broadly
`identified region.
`
`
`
`
`
`
`
`
`
`
`
`
`
`The Relationship of Age and Sex to the Thickness
`
`
`
`
`and Numbers of Cell Layers of
`the Stratum
`
`
`
`
`
`
`
`Corneum
`
`
`
`
`
`
`
`
`
`The importance of age and sex as variables in
`
`
`
`
`
`
`
`determining the thickness and numbers of cell
`
`
`
`
`
`
`
`
`
`layers of the stratum corneum has been given
`
`
`
`
`
`
`varying degrees of empha:
`me literature. Both
`
`
`
`
`
`
`
`
`cases have been supported with data. A review of
`
`
`
`
`
`
`
`
`
`the early literature illustrates this controversy [15]
`
`
`
`
`
`
`
`
`
`
`which appears to be still unresolved. More re-
`
`
`
`
`cently. Black [‘23] has determined the entire skin
`
`
`
`
`
`thickness to decrease after 65 years of age. but to
`
`
`
`
`
`
`
`do so without any relationship to sex. Maximum
`
`
`
`
`
`
`
`thickness has been lbund in individuals of 35 years
`
`
`
`
`
`
`
`
`
`
`
`
`
`of age [24]. Plewig [25] recognized larger cells in
`
`
`
`
`the stratum corneum of females in all areas investi-
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`gated. By contrast. Humphries and Wildnauer [26]
`
`
`concluded that there is “no apparent correlation
`
`
`
`
`
`
`
`
`between the variation in sample thickness. age. or
`
`
`
`
`sex of the individual."
`
`
`
`
`The mean values of thickness and cell numbers
`
`
`
`
`
`
`
`obtained for male and female subgroups are not
`
`
`
`
`
`
`
`
`
`
`
`
`significantly nor consistently greater for either
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`

`

`422
`
`
`THE JOURNAL OF {NVESTIGATNE DERMATGEDGY
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`group. Our data cannot support a relationship of
`age and sex to the overall thickness and numbers of
`
`
`
`
`
`
`
`
`
`
`cell layers of the stratum c'orneurn. but the calcu-
`
`
`
`
`
`
`
`
`
`
`lated thicknesses of individual horny cells in all
`
`
`
`
`
`
`
`
`
`cases are in accord with a larger cell size for all
`
`
`
`
`
`
`
`
`
`
`regions of females as reported by Plewig [25].
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Relationship of Thickness [Nam ber of Cell Layers)
`
`
`
`
`
`of the Stratum Comeum to Permeability
`
`
`
`Two investigations that have been designed to
`
`
`
`
`
`
`
`
`
`explore the kinetics of permeability in several
`
`
`
`
`
`
`anatomical regions of the body were carried out in
`
`
`
`
`
`
`
`
`
`vivo by Feldma'nn and Maibacb Iljand Maibach et
`
`
`
`
`
`
`
`
`
`
`
`al [2]. By measuring the amount of “C present in
`
`
`
`
`
`
`
`
`
`
`the urine after application of “Ghydrocortisone to.
`
`
`
`
`a given site.
`it. was determined that the rate of
`
`
`
`
`
`
`
`
`
`
`
`absorption of that compound through the skin of
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`the back is 1.7 times more rapid than the rate of
`
`
`
`
`
`absorption through the flexor forearm [1 ]. Penetra-
`
`
`
`
`
`tion of parathion and malathion is 2.1 times and
`
`
`
`
`
`
`
`
`1.4 times greater through the abdominal skin when
`
`
`
`
`
`
`
`
`compared with the flexor forearm [2 ]. Both studies
`
`
`
`
`
`
`suggest that the skin of the flexor forearm is a more
`
`
`
`
`
`
`
`
`
`
`resistant barrier than the skin of either the abdo-
`
`
`
`
`
`
`
`
`men or back. The thickness and cell layer measure-
`
`
`
`
`
`
`
`
`me