Tue JouRNAL oF INVESTIGATIVE DerMATOLOGY, 62: 415-422, 1974
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`Copyright © 1974 by The Williams & Wilkins Co.
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`Val. 62, No, 4
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`Printed in U.S.A.
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`REGIONAL DIFFERENCES IN THE THICKNESS (CELL LAYERS) OF THE HUMAN
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`STRATUM CORNEUM: AN ULTRASTRUCTURAL ANALYSIS*
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`KAREN A, HOLBROOK. Pu.D., ano GEORGE F. ODLAND, M.D.
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`~*
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`ABSTRACT
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`The importance of the stratum corneum as the rate-limiting barrier to percutaneous
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`penetration has been well documentedin the literature. Data have also been reported which
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`suggest that the barrier function of this zone varies among different regions of the body.
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`However,little attention has been given to regional variation of two morphologic parameters
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`known to affect permeability—thickness and number ofcell layers. In the present study.
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`significant regional variation in both the mean thickness and the mean number of cell layers
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`has been documentedfor four selected, sample regions of the body of a population ofsix adult
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`volunteers, and for two more homogeneous subgroups separated by sex and age. While the
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`pooled data from the total population and the pooled data from the male and female
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`subgroups are in general agreement, it has been shown that there is also marked individual
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`variation within a region that is characteristic and specific for each individual, The number
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`of cell layers appears to account for the variation in thickness.
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`in the permeability of
`Widespread interest
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`| human skin has generated a plethora of experimen-
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`tal investigations using in vivo and in vitro tech-
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`* niques. Several of the in vivo studies were carried
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`out by measuring the diffusion of a radioactively
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`“labeled compound through the epidermis and der-
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`mis into the blood vascular system of living sub-
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`“jects [l, 2]. Other investigators have used in vitro
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`. model systems in their experimentation [3]. In the
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`latter method, permeability of human cadaver skin
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`+ is measured. The measurements ofthe kinetics of
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`transport that are obtained from both experimen-
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`tal approaches would not be expected to differ
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`significantly on the basis that only the nonviable
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`~cells of the stratum corneum serve as the rate-
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`5 limiting barrier to the passage of substances across
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`the epidermis [4].
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`in part,
`The rate of diffusion of molecules is,
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`dependent upon the length of the diffusion path-
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`+ way, which in this instance is the thickness ofthe
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`stratum corneum. However, data on the thickness
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`reof the stratum corneum are limited and general-
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`ized and do not systematically take into account
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`“the possibility of significant
`regional variations
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`, which might be implied from the demonstration of
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`regional variation in percutaneous absorption |[1,
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`m2):
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`The studies to investigate the differences in
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`»athickness and numbers ofcell layers of the stratum
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`corneum from different regions of the body have
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`+ failed to establish controls for preservation of the
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`full thickness of the samples [5, 6]. Nonetheless,
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`the importance of these two parameters of the
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`‘
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`stratum corneumto the interpretation of permea-
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`bility data has been recognized: “Strictly speak-
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`ing, such comparisonsof[rates of permeation | are
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`not valid unless one corrects for horny layer thick-
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`ness or alternatively for numberofcell layers” [7 |.
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`It was,
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`the objective of the present
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`study to apply methods that would assure preser-
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`vation of an intact, full-thickness stratum corneum
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`and to evaluate quantitatively the regional varia-
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`tion in total thickness and numbers ofcell layers of
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`this epidermal zone using electron microscopy.
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`MATERIALS AND METHODS
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`Specimens were obtained from the abdomen, flexor
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`forearm, anterior thigh, and posterior inferior iliac re-
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`gion of six, healthy, human volunteer subjects,
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`white males and three white females within the age group
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`of 25-31. The areas to be sampled were gently cleansed by
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`a single stroke with a 70% alcohol wipe prior to biopsy
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`with a high-speed, electric rotary drill fitted with a
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`2.5-mm biopsy punch. The tissue “plug” obtained was
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`then marked in a manner to assure the preservation of
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`full-thickness stratum corneum during further process-
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`ing. Small sheets of lens paper were placed above and
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`below the core oftissue. The “sandwiched” preparation
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`was then set onto a hollow plastic cylinder (prepared by
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`trimming away the bottom of a BEEM capsule) and
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`secured in place with an open-top cap (Fig. 1). The
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`assembled capsule with the paper-enclosed biopsy sam-
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`ple was carried through fixation, dehydration, and em-
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`bedment for electron microscopy. Thus, cell layers which
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`might have become detached during processing were
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`trapped beneath the lens paper and could be included in
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`the measurements of thickness and the counts ofcell
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`layers
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`In pilot assays of
`this method,
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`marking the surface with AgNO, and particulate carbon
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`prior to removal of the biopsy specimen established that
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`the technique of biopsying did not remove the outer layer
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`of the stratum corneum.
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`Tissue was fixed for electron microscopy in 2 parts of
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`2% osmium tetroxide buffered with 1 part of 0.2 M
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`s-collidine at
`low temperature for 2 hr, dehydrated
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`through a graded series of alcohols, and embedded in
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`L'OREALUSA,INC. EX. 1017
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`This work was supported by USPHS Grants DE-02600,
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`AM-08368, and GM-16598 from the National Institutes of
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`“4Health, and by a grant from the Procter and Gamble
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`Company, Cincinnati, Ohio.
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` *From the Department of Biological Structure (KAH
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`and GFO), and the Department of Medicine, Division of
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`+ Dermatology (GFO), University of Washington Schoolof
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`Medicine, Seattle, Washington 98195.
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`a
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`415
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`L'OREAL USA, INC. EX. 1017
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`416
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`THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
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`Plastic ring with
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`open lid
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`the plastic
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`Epon 812
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`cylinder was cut away leaving the tissue and enclosing
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`paper to be oriented on metal stubs with the stratum
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`a7 «
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`corneum positioned parallel to the axis of the microtome
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`chuck such that tissue sections would be cut
`in a plane
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`Skin
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`perpendicular to the skin surface. Thick sections (1.5 um)
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`biopsyto——_—___L
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`were prepared with glass knives and thin sections, in the
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`Lens poper
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`markers
`silver interference color range, were cut through both the
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`tissue and lens paper with a diamond knife mounted on a
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`Reichert Om U2 ultramicrotome. Several
`thin sections
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`were cut at each of 8-10 uniformly separated intervals
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`1:
`to assure
`Technique designed by M. Hoff
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`preservation of full-thickness stratum corneum during
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`processing of tissue for electron microscopy.
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`Fixation,
`dehydrolion
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`cea?
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`Assembled copsule,
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`poper and biopsy
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`LENS PAPER
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`Fic. 2:
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`(a) Light micrograph showing the lens paper marker above human epidermis.
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`1 765)
`micrograph of human epidermis and lens paper marker.
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`(«
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`750)
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`(b) Electron
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`THICKNESS OF STRATUM CORNEUM
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`A417
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`[t was estimated that measurements
`each skin sample.
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`were madeover a total of 20-25 lineal mmofthe stratum
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`corneum. For the purpose of evaluating the thickness, a
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`line was drawn through the stratum corneum perpen-
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`dicular to the skin surface on each micrograph and
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`‘through the entire biopsy specimen. All sections were
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`double stained with saturated uranyl acetate and Rey-
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`nold's (9]
`lead citrate. Sections were examined in a
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`Philips 200 electron microscope.
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`Fifty electron micrographs were photographed from
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`rey =
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`(a, b) Stratum corneum from the posterior inferior iliac region. Note the variation in the thickness along the
`Fic. 3:
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`+ photographed segment. (a, x 3,865; b,
`x 4,050) (c) Stratum corneum from the thigh. The thickness is measured as the
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`height of the black line and the number ofcells intersected are counted. (» 5,680)
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`a
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`418
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`THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
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`“
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`Fic. 4; Mean thickness and mean numbers of cell
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`layers of the stratum corneum for the four regions sam-
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`pled from six volunteer subjects. (Electron micrograph
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`segments = 6,635)
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`measured from the deepest layers to the most superficial.
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`The number ofcells intersected by that line were then
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`counted (Fig. 3c), On several micrographs more than one
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`measurement was obtained when the thicknéss of the
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`stratum corneum showed obvious variation along its
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`photographed length (Figs. 3a,.h).
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`The measurements were then typed onto IBM com-
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`puter cards and submitted to the CDC 6400 computerfor
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`Statistical analyses. Mean values, standard deviations,
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`and p-values of comparisons were computed using ver-
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`sion 2.3 of the SPSS Statistical Package for the Social
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`Sciences [10).
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`RESULTS
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`It was the primary objective of this study to
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`document regional variation in the thickness and
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`numberofcell lavers of the stratum corneum,first
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`for a selected sample population and then for two,
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`more homogeneous subgroups ofindividuals within
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`that population. The criteria used to establish the
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`latter groups were sex and age. The three male
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`subjects selected were of ages 25-27 and the three
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`female subjects were 30-31 years of age. The
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`consistency of the data from each region and each
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`individual was also considered in the interpreta-
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`tion ofresults.
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`Pooled Data from All Subjects
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`Figure 4 is a graphic representation of the mean
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`values for both thickness and numbers ofcell
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`layers of the stratum corneum from the four body
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`regions tested. Each bar represents a composite
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`mean value that was obtained as an average value
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`of the individual means of the data from the six
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`subjects selected. With the mean value of the
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`abdominal stratum corneum serving as the stan-
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`dard for comparison, both thickness and numbers
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`of cell
`layers from the flexor forearm, thigh, and
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`back were compared byuse of the t-test and were
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`found to be significantly different at a confidence
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`level of p < .0001. The large standard deviations —
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`calculated for these pooled data reflect
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`(1)
`that
`the stratum corneum in a given
`tures:
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`sampled region is variable in both thickness and
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`numbers ofcell layers among the subjects studied,
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`and (2) that a sample length of stratum corneum*
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`measured from any region of each individual is not
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`consistent in thickness and numbers ofcell layers ”
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`(Figs. 3a,b). The individual data from each body
`
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`region of each subject are expressed in Tables |
`
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`
`(abdomen), IT (flexor forearm). II] (thigh), and IV
`
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`(back).
`
`the thickness of the
`It was also found that
`
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`
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`
`
`
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`
`
`
`stratum corneum appears to vary proportionately
`
`
`
`with the number of cell layers comprising that zone’
`
`
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`
`
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`of the epidermis. This proportionality has been
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`calculated by dividing the mean thickness of each
`
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`region by the mean numberofcell layers for that
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`region. The resulting value also provides an aver-
`
`
`
`In,
`age dimension for
`individual cell
`thickness.
`
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`
`
`three of the four regions the cell
`thickness was
`
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`
`
`determined to be .17-.18 um. However, by this+
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`
`
`ZA Thithnavs
`[27 no ot cnt
`
`tayere
`
`TABLE|
`
`
`Meanthickness (um) and mean number of cell layers of
`
`
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`
`
`
`
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`
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`the stratum corneum fram the abdomen of six human
`
`
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`
`
`
`
`subjects
`
`=
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`= oct|Tew | ==
`’ “*
`¥ | a
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`tees + a
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`1 7
`= els
`— De et
`olgmm~
`
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`wi
`
`
`
`TABLEII
`
`
`
`Mean thickness (um) and mean numberofcell lavers of
`
`
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`the stratumcorneum from the flexor forearm of six
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`human subjects
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`

`

`z
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`THICKNESS OF STRATUM CORNEUM
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`419
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`
`
`SUAIAVT11351°‘ON
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`
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`‘method of calculation the cells of the abdomen
`
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`
`
`were estimated to have a greater average thickness
`
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`.22 wm. These results appear to support
`of
`a
`
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`generalization that regional variation in the thick-
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`ness of stratum corneum is related to the number
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`, of cell layers that comprise it within a given region;
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`the data appear to lend less support to an alternate
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`+ explanation of the regional differences as a conse-
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`quence of extensive variation in individual cell
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`thickness. These conclusions, although drawn from
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`mean values computed from the total population
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`of subjects, are borne out by the data that were
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`_.summarized independently for the male and fe-
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`male subgroups.
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`stratum corneum thickness and numbers ofcell
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`layers of all female subjects. The same data are
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`Fie. 5: Mean thickness and mean numberofcell layers
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`illustrated for the male subjects in Figure 6,
`In
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`of the stratum corneumfor the four regions sampled from
`Se
`c
`:
`:
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`both groups,
`the mean thickness of
`the stratum the male subgroup. (Electron micrograph segments x
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`6,365)
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`Pa
`ianownT
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`FLEXOR
`FOREARM
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`TABLEIII
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`Mean thickness (um) and mean numberof cell lavers of
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`the stratum corneum from the thigh of six human
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`i; debi Per area
`
`7
`.
`
`s
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`&
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`-
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`/
`—|
`
`10:
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`* Pooled Data from Male and Female Subgroups Figure 5 graphically displays the mean valuesfor
`
`THICKNESSofSTRATUMCORNEUM
`subjects
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`|
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`8
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`37
`5
`8
`e
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`on
`gt=
`BACK
`THIGH
`FLEXOR
`ABDOMEN
`FOREARM
`Fic. 6: Mean thickness and mean number of cell
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`layers of the stratum corneum for the four regions sam-
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`pled from the female subgroup. (Electron micrograph
`
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`segments « 6,365)
`
`corneum is significantly different (p < .0001) when
`
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`compared with the mean abdominal dimensions.
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`The mean numbers ofcell layers were alsosignifi-
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`cantly different (p < .0001) among the four regions
`
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`of the male subjects, but did not differ significantly
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`.154)
`(p =
`in a comparison of the abdomen and
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`back of female subjects. It may be noted that the
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`calculated individual cell thickness is greater for
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`the female subjects as a group and for each female
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`subject
`individually when compared with the
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`group of males and with the individual male
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`subjects. Again, male and female group data
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`indicate that there are thicker cells in the abdomi-
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`nal region. The pooled data from the total popula-
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`tion and the data from the two subgroups are in
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`good agreement.
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`:
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`zz Thich hee
`cell eyes
`[
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`|
`es
`
`oe
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`
`
`hh
`
`&
`
`f
`
`-?
`
`
`
`TABLE IV
`
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`
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`Mean thickness (um) and mean numberofcell layers of
`
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`the stratum corneum from the back of six human subjects
`
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`
`
`(Sinn ]am [oo wom mcroen ow]MEE™ oo
`[GSDmer
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`aoe
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`
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`>
`
`ra
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`[wen
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`”w|e
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`

`

`
`420
`
`THE JOURNAL OF INVESTIGATIVE DERMATOLOGY
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`Individual Data
`
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`
`
`It may be seen from Tables I-IV that there is
`
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`significant variation among individuals in both
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`thickness and numbers ofcell layers of the stratum
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`corneum from the regions sampled. Having estab-
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`lished the individual variation, we then considered
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`whether it would be possible to obtain a value for
`
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`each subject that could be used to “correct” the
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`data for individual variation and obtain theoretical
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`values for thickness and numbersofcell layers that
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`would be equivalent among subjects. The mean
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`thickness and the mean numberofcell layers from
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`the abdomen, flexor forearm. thigh, and back of
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`each subject were averaged to obtain an overall
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`“body value” for thickness and numbers of cell
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`layers characteristic of each subject. These aver-
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`ages were then used to obtain a mean value for
`
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`thickness and numbers of cell layers for the group
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`of subjects, Deviation from this mean was calcu-
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`lated for each subject and that value was used as a
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`factor to adjust the individual regional data. The
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`results of this method to correct
`the data only
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`further emphasized and supported the conclusion
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`of specific individual variation in a region among
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`the subjects of a population.
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`
`
`DISCUSSION
`
`This study is the only work to date in which
`
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`measurements of the thickness and numbers of cell
`
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`layers of the stratum corneum are compared from
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`several body regions of the same subject. Blair [5]
`has reported the mean numberof horny ceil layers
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`and mean horny cell thickness characteristic of the
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`interscapular region and the extensor forearm, but
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`the biopsies studied from these two regions appear
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`to have been obtained from different subjects. The
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`author’s primary concern was to adopt and elabo-
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`rate a method to enhance visualization of horny
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`cell layers and not tocompare the stratum corneum
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`from the two regions. Baker and Kligman [7]
`acknowledged regional variation in the stratum
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`corneum thickness and/or numbers of cell layers,
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`but they used this information only to advocate
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`care in interpretation of permeability data.
`In
`another study in which functional differences in
`
`
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`the stratum corneum were compared, Smith,
`
`
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`Fischer, and Blank [11] compared the numbers of
`
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`layers of cells from the abdominal and scrotal
`
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`stratum corneum by repeatedly stripping this
`
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`layer. Rushmer and co-workers
`reported
`[12]
`
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`their findings on the total skin (epidermis plus
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`dermis) thickness of the scalp,
`forehead, back,
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`abdominal, thigh, wrist, and palmar surfaces and
`
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`included light microscopic measurements of the
`stratum corneum from the flexor forearm, sole,
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`scrotum, and callus.
`
`
`
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`It is therefore apparent that while many authors
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`have reported values of thickness and numbers of
`cell layers of the stratum corneum, their results
`
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`have been obtained by diverse methodology. Some
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`of the techniques which have been used to estimate
`
`both of these parameters include: (1) scotch tape
`
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`stripping to remove the cell layers; the numbers of
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`strippings were correlated with the numbers ofcell
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`layers {13};
`(2) treatment of paraffin-embedded.
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`and frozen biopsies with alkali to cause swelling,
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`hence better visualization and more accurate ,
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`counting of the horny cell layers [14]; (3) applica-
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`tion of standard chemical fixation, paraffin em-
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`bedment, and staining procedures for histologic
`
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`sections; thickness was measured with a microme-
`
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`ter eyepiece [15]; (4) mechanical measurement of
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`dried tissue by means of a modified Starett gauge
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`[6]; and (5) preparation of tissue by chemical
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`fixation and plastic embedment for electron mi-
`
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`croscopy; measurements were made from electron ,
`micrographs [16]. No techniques have been de-
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`scribed in any of thése studies to insure full
`
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`thickness preservation of stratum corneum.
`
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`
`r
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`
`
`General Body Thickness of Human Stratum
`Corneum
`
`The thickness of the stratum corneum has been,
`
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`too frequently expressed in a single value
`all
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`intended to be representative of the body as a |
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`whole. These figures are probably not a true
`
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`average calculated fromseveral body regions, but
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`rather were based on an isolated measurement,
`
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`Values of 13.2 um [17], 14 um [18], and 15 ym [19]”
`
`
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`
`
`have been reported as an average thickness of dry
`
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`
`stratum corneum. By comparison, our “body aver-
`
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`ages” calculated as the average value of the mean
`
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`thicknesses of the four regions ranged from 8.7-12.9
`
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`yum. Only the flexor forearm, and in one case the
`
`thigh, had a mean thickness within the range
`
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`assumed as an average for the whole bodyby other
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`
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`authors,
`
`
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`
`
`Again, without reference to regional variation, ~
`
`the stratum corneum has been discussed as ap-
`
`
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`
`
`
`
`proximately 15 cell
`layers thick except
`for the
`
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`
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`palm, sole, scrotum, hand, and foot
`[14] or has
`
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`been described in ranges of 10-25 cell layers [20]
`
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`and 15-30 cell layers with 20-22 most frequently
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`counted [21]. In this parameter, our data for the
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`mean numbers of cell
`layers of the four regions*
`
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`sampled lie within a more narrow range of 14-23.3
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`cells. Onlyone exceptional measurement, from the —
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`flexor forearm, of 30 cells was counted. “Body
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`
`averages” for the numbers of cell layers compared
`
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`
`
`favorably (15.6—22.8) with the range expressed
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`from the individual data.
`
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`
`Regional Variation in the Stratum Corneum
`
`
`
`
`
`It has been commonly recognized but poorly
`
`documented that the thickness of the epidermis as
`
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`
`
`
`
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`
`
`a whole [15, 12] and of the stratum corneum
`
`
`portion of the epidermis specifically, vary in thick-
`
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`
`
`ness and numbers ofcell layers in different regions
`
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`
`
`of the body. We have selected four regions of the«
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`
`
`
`bedy to document
`this variation. The data ob-
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`
`
`tained in this study and the measurements which
`
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`
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`have been reported in the literature for the same
`
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`
`
`
`régions are compared in Table V.
`
`
`
`
`
`
`
`
`

`

`
`
`
` aee Hector.
`
`, Flexor
`
`forearm
`
`
`
`“8.2 um mean
`
`
`*6.9-9.8 range
`
`
`
`
`15 um
`
`
`
`*12.9 um mean
`
`
`*8.1-16.2 um range
`
`
`
`
`
`Thigh
`
`
`
`8.5-13.8 wm
`
`
`
`«
`
`*10.9 vm mean
`
`
`*7 7-15.3 range
`
`
`
`
`1 Back
`
`
`
`
`
`12 um
`
`
`
`6.2-19.1
`
`
`11.8 mean
`
`
`
`
`
`Rushmeret al [12]
`
`
`
`Humphries & Wildnauer
`
`
`[26 | (measurements
`
`
`obtained on “‘leg”)
`
`
`
`
`
`
`Blair [5]
`
`
`Odland [28]
`
`
`
`
`
`*18 mean
`
`*15-20.9 range
`
`
`
`10.2-23.4
`
`
`25
`
`
`
`“21.6 mean
`
`*16.7-30 range
`
`
`
`No reported
`
`
`measurements
`
`
`
`
`
`*19.3 mean
`
`
`*14.3-22.7 range
`
`
`
`Humphries & Wildnauer
`
`
`[26]
`
`
`
`
`9.6-20.0
`
`
`
`Anderson & Cassidy [6]
`
`
`
`
`(measurements obtained|
`
`from “hip”)
`
`
`
`
`
`14-28
`
`
`19 mean
`
`
`
`
`
`
`
`Blair [5] (measurements
`
`obtained from interscap-
`
`ular region)
`
`
`
`Anderson & Cassidy [6]
`
`
`
`(measurements obtained
`
`from “hip"’)
`
`
`
`
`
`
`
`*9.4 um mean
`
`
`
`|
`*8.2-11.3 range
`
`
`
`
`* Measurements obtained in the present study.
`
`
`
`
`
`
`
`
`
`
`*15.8 mean
`
`“14-21.1 range
`
`
`
`
`
`,
`
`.
`
`7
`
`
`
`
`
`THICKNESS OF STRATUM CORNEUM
`
`
`
`
`
`
`421
`
`
`TABLE V
`
`Comparison of measurements of thickness and numbersof cell layers reported in the literature and measurements
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`obtained in the present study
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`Abdomen
`
`
`
`13 wm
`
`
`40 um
`
`
`
`
`Scheuplein [18] |2
`
`
`
`Blank & Scheuplein [27]
`
`
`
`
`
`
`18
`
`
`
`
`
`
`
`
`
`
`
`
`Reference
`Brody[16]
`
`
`
`
`Smith, Fischer, & Blank
`
`
`[11]
`
`
`
`
`
`
`
`
`
`
`Number of cell layers. In the majority of exam-
`
`
`
`
`ples, our measurements for the number ofcell
`
`
`
`
`
`
`
`
`
`
`
`
`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
`
`
`
`
`
`
`
`
`ofall layers in tissue processing.
`
`
`
`
`
`
`
`Thickness. There is considerably more variance
`
`
`
`* between our measurements of thickness and those
`
`
`
`
`
`
`
`, reported in the literature. Again, methodsoftissue
`
`
`
`
`
`
`preservation may explain these discrepancies, The
`
`
`
`
`amount of water allowed to remain in the tissue
`
`
`
`
`
`
`
`
`
`
`during processing can accountfor significant alter-
`
`
`
`
`
`ation in this measurement. The stratum corneum
`
`
`
`
`
`
`
`
`
`
`can inerease its thickness severalfold when fully
`
`
`
`
`
`
`
`4 hydrated.
`Idson [22] has reported that a dry
`
`
`
`
`
`
`
`
`
`stratum corneum of 15 um thickness can expandto
`
`
`
`
`
`
`
`48 um 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 numbersof cell layers from several
`
`
`
`
`
`
`
`
`
`4 studies is the precise location of sampling. Identifi-
`
`
`
`
`
`
`
`
`cation of 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 “‘back’’ 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:
`-. une literature. Both
`
`
`
`
`
`
`
`
`
`
`
`
`
`cases have been supported with data. A review of
`
`
`
`
`the earlyliterature 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 found in individuals of 35 years
`
`
`
`
`of age [24]. Plewig [25] recognized larger cells in
`
`
`
`
`
`
`
`
`
`the stratum corneum offemales 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 INVESTIGATIVE DERMATOLOGY
`
`
`
`
`
`
`
`group. Our data cannot support a relationship of
`
`
`
`
`
`
`
`
`age and sex to the overall thickness and numbers of
`
`
`
`
`
`
`
`
`
`
`cell layers of the stratum corneum, but the caleu-
`
`
`
`
`
`
`
`
`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].
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`1973
`
`
`
`. Baker H, Kligman
`
`
`
`
`
`
`
`AM: A simple in vivo method for
`
`studyingthe permeability of the human stratum
`
`
`
`
`
`
`
`corneum. J Invest Dermatol 48:273-274, 1967
`
`
`
`
`
`» Luft
`JH: ogee in epoxy embedding
`
`
`
`
`
`
`paca J Biophys Biochem Cytol 9:409-414,
`
`
`
`
`
`|
`,
`
`. Reynolds BS: The use oflead citrate at high pH as an ©
`
`
`
`
`
`
`
`
`
`
`
`
`
`electron-opaque stain in electron microscopy. J
`
`
`
`
`
`
`Cell Biol 17:208-212, 1963
`
`
`
`
`Nie N, Bent DH, Hull CH: SPSSStatistical Package
`
`
`
`
`
`
`
`for the Social Sciences. New York, McGraw-Hill,
`
`
`
`
`
`
`1970
`
`
`
`
`
`Smith JG Jr, Fischer RW, Blank H: The epidermal
`
`
`
`
`barrier: acomparison between scrotal and abdomi-
`
`
`
`
`
`nal skin. J Invest Dermatol 36:337-344, 1961
`
`
`
`
`
`
`Rushmer RF, Buettner KJK, Short JM, Odland GF:
`
`
`
`
`
`
`
`
`
`
`
`The skin. Science 154:343-348, 1966
`. Pinkus H: Examination of the epidermis by the strip
`
`
`
`
`
`
`
`
`
`
`
`method of removing horny layers. I. Observations
`
`
`
`
`
`
`
`
`
`
`
`
`
`on the thickness of the horny layer, and on mitotic
`
`gaafter stripping. J Invest Dermatol 16:383-
`
`
`
`
`1
`:
`
`
`
`
`Christophers E, Kligman AM: Visualization of cell
`
`
`
`
`
`
`
`
`
`
`layers of thestratum corneum. J Invest Dermatol
`
`
`42:407-410, 1964
`
`
`
`15, Southwood
`pod WFW: The thickness of the skin. Plast
`
`
`
`
`
`
`
`
`
`
`
`Reconstr Surg 15:423-429, 1955
`
`
`
`
`BrodyI: An electron microscopic study of thef