ArticlePDF Available

Abstract and Figures

Functional differences between infant and adult skin may be attributed to putative differences in skin microstructure. The purpose of this study was to examine infant skin microstructure in vivo and to compare it with that of adult skin. The lower thigh area of 20 healthy mothers (ages 25-43) and their biological children (ages 3-24 months) was examined using in vivo noninvasive methods including fluorescence spectroscopy, video microscopy, and confocal laser scanning microscopy. Stratum corneum and supra-papillary epidermal thickness as well as cell size in the granular layer were assessed from the confocal images. Adhesive tapes were used to remove corneocytes from the outer-most layer of stratum corneum and their size was computed using image analysis. Surface features showed differences in glyph density and surface area. Infant stratum corneum was found to be 30% and infant epidermis 20% thinner than in adults. Infant corneocytes were found to be 20% and granular cells 10% smaller than adult corneocytes indicating a more rapid cell turnover in infants. This observation was confirmed by fluorescence spectroscopy. Dermal papillae density and size distribution also differed. Surprisingly, a distinct direct structural relationship between the stratum corneum morphology and the dermal papillae was observed exclusively in infant skin. A change in reflected signal intensity at approximately 100 mum indicating the transition between papillary and reticular dermis was evident only in adult skin. We demonstrate in vivo qualitative and quantitative differences in morphology between infant and adult skin. These differences in skin microstructure may help explain some of the reported functional differences.
Content may be subject to copyright.
Infant Skin Microstructure Assessed In Vivo
Differs from Adult Skin in Organization
and at the Cellular Level
Georgios N. Stamatas, Ph.D.,* Janeta Nikolovski, Ph.D.,Michael A. Luedtke, M.S.,à
Nikiforos Kollias, Ph.D.,àand Benjamin C. Wiegand, Ph.D.
*Baby Science & Technology, Johnson & Johnson Consumer France, Issy-les-Moulineaux, France, Advanced
Technologies, Johnson & Johnson Consumer and Personal Products Worldwide, Skillman, NJ, USA, àMethods and
Models Development, Johnson & Johnson Consumer and Personal Products Worldwide, Skillman, NJ, USA.
[Correction made after online publication on Oct. 4th 2009]
Abstract: Functional differences between infant and adult skin may be
attributed to putative differences in skin microstructure. The purpose of this
study was to examine infant skin microstructure in vivo and to compare it with
that of adult skin. The lower thigh area of 20 healthy mothers (ages 25–43) and
their biological children (ages 3–24 months) was examined using in vivo
noninvasive methods including fluorescence spectroscopy, video micros-
copy, and confocal laser scanning microscopy. Stratum corneum and supra-
papillary epidermal thickness as well as cell size in the granular layer were
assessed from the confocal images. Adhesive tapes were used to remove
corneocytes from the outer-most layer of stratum corneum and their size was
computed using image analysis. Surface features showed differences in
glyph density and surface area. Infant stratum corneum was found to be 30%
and infant epidermis 20% thinner than in adults. Infant corneocytes were
found to be 20% and granular cells 10% smaller than adult corneocytes indi-
cating a more rapid cell turnover in infants. This observation was confirmed
by fluorescence spectroscopy. Dermal papillae density and size distribution
also differed. Surprisingly, a distinct direct structural relationship between the
stratum corneum morphology and the dermal papillae was observed
exclusively in infant skin. A change in reflected signal intensity at
100 lm
indicating the transition between papillary and reticular dermis was evident
only in adult skin. We demonstrate in vivo qualitative and quantitative differ-
ences in morphology between infant and adult skin. These differences in skin
microstructure may help explain some of the reported functional differences.
Healthy infant skin is often described as soft and tender
and is frequently presented as an ideal state of skin aspired to
by adults. On the other hand, infant skin is also described as
‘‘fragile’’ and ‘‘sensitive’’ and is prone to dermatitides and
infections (1). Of particular importance is the recent increase
in the incidence of infantile atopic dermatitis (2). A compa-
Address correspondence to Georgios N. Stamatas, Ph.D.,
Johnson & Johnson Consumer France, 1 rue Camille Desmoulins,
Issy-les-Moulineaux 92130, France, or e-mail: gstamat@its.jnj.com.
DOI: 10.1111/j.1525-1470.2009.00973.x
2009 Wiley Periodicals, Inc. 125
CLINICAL AND LABORATORY INVESTIGATIONS
Pediatric Dermatology Vol. 27 No. 2 125–131, 2010
rative study of infant and adult skin physiology is bound to
shed light on the reasons for this special status of infant skin.
The barrier function and the water holding and
transportpropertiesofinfantstratumcorneum(SC)
have been shown to be different from an adult and con-
tinuetoevolvethroughthefirstyearoflife(3).InfantSC
was found to have higher water content and higher trans-
epidermal water loss rates at rest, absorb more water and
loose excess water faster than adult SC. Many of these
differences may be explained by careful examination of
the underlying skin microstructure.
Advances in noninvasive methods such as confocal
laser scanning microscopy (CLSM) have made the study
of skin microstructure in vivo possible, avoiding the need
for painful biopsies, as well as the artifacts introduced by
handling and fixing the sample required for histological
samples examination. By focusing the incident light on
the skin at different depths and scanning its position in
the plane parallel to the skin surface, one can obtain
images corresponding to ‘‘optical sections’’ through the
skin volume, in contrast to the vertical sections of his-
tology (4). This technology has been applied to the study
of adult skin physiology (5) and pathology of several
dermatological conditions [for reviews see (4,6,7)], but to
our knowledge it has not yet been used in the study of
infant skin.
Another useful noninvasive method is in vivo fluo-
rescence spectroscopy, which has been used to assess the
proliferation rate of the epidermal cells (8–10). This
signal has been shown to decrease with age in adults (11),
but there have been no reports to date about its use on
infant skin. In this study, we employed in vivo nonin-
vasive methods to address the question whether infant
skin microstructure is different from that of an adult at
the organ level (epidermal thickness, epidermal organi-
zation) and at the cellular level (cell size and cell density).
MATERIALS AND METHODS
Clinical Protocol
The study was performed under approval from an
independent institutional review board and following
the principles of the Declaration of Helsinki. Twenty
mothers from the New Jersey area at 25–46 years of age
and their biological infants at ages 6–24 months partic-
ipated in the study. Adult subjects signed a written in-
formed consent for themselves and their participating
children. Only healthy individuals were recruited. The
skin phototypes of the adult subjects were I–III on the
Fitzpatrick scale. The infant population was fair com-
plexioned and equally distributed between boys and girls.
Subjects were instructed to avoid use of skin care prod-
ucts on the arms and legs for at least 24 hours before the
measurements. Visibly distressed or crying infants were
excluded. Measurements were performed on the upper
inner arm, the dorsal forearm, or the lower thigh area as
described below.
Video Microscopy
A video microscope (HiScope Systems Co., Closter, NJ)
wasusedtoacquireinvivolightreectanceimagesofthe
skin surface with a magnification of 100·. The micro-
scope camera was calibrated before image acquisition
using a white reflectance standard (Minolta, Ramsey,
NJ). The final image corresponded to a skin area of
2.7 mm ·2.1 mm.
Confocal Laser Scanning Microscopy
The skin sites of interest were examined in vivo using a
reflectance CLSM (Vivascope
1500, Lucid Inc., Hen-
rietta, NY) equipped with a laser at 785 nm (laser power
<25 mW at the tissue surface) and a oil immersion 30·
objective of numerical aperture 0.9 NA. This microscope
generates a series of consecutive optical sections every
3.125 lm of increasing depth. Imaging starts at the top
layer of the SC and progresses down through the epi-
dermal layers, the dermal epidermal junction, and the top
layers of the dermis. Each optical section corresponded
to a skin area of 0.5 mm ·0.5 mm. The laser power was
adjusted to increase the signal-to-noise ratio for the
deeper sections and its value was recorded for each cor-
responding image. The sequential optical sections were
analyzed as explained below for the measurement of SC
and epidermal thickness and they were reconstructed to
form three-dimensional images using the 3D Construc-
tor
plug-in to Image Pro software (Media Cybernetics,
Bethesda, MD). The lower thigh area was selected
forthesesmeasurementsto reduce infant motion
during acquisition. Three replicate stacks within a
4mm·4 mm area were sampled and then averaged.
CLSM Image Analysis
The SC thickness was calculated as the number of images
from the first image (top corneocyte layer) to the image
just before the one where granular cells can be detected,
times the imaging step (3.12 lm). Similarly, the epider-
mal thickness was calculated as the number of images
from the top corneocyte layer to the image just before the
one where the top of the dermal papilla can be detected,
times the imaging step. The size of cells at the SC and
granular layer was analyzed using the Image J software
developed by the National Institute of Health (http://
126 Pediatric Dermatology Vol. 27 No. 2 March April 2010
rsb.info.nih.gov/ij/). Finally, the average grayscale
intensity was calculated for each optical section (to
minimize edge artifacts the central image area was used
only) and normalized to the corresponding laser power.
Thus, depth profiles of the backscattered light intensity
could be constructed.
Cell Size Analysis
Corneocytes were removed from the skin surface at the
upper inner arm, dorsal forearm, and thigh using adhe-
sive tapes (D-Squames, CuDerm Corporation, Dallas,
TX). Each tape was applied uniformly on the skin and
was removed after 1 min. Images of the removed
corneocytes on the tapes were acquired using a video
light microscope (HiScope Systems Co., Closter, NJ).
Thefinalimagecorrespondedtoanareaof
2.7 mm ·2.1 mm. Images of individual cells were ana-
lyzed for cell area and perimeter using the Image J
software.
Fluorescence Spectroscopy
To evaluate the keratinocyte proliferation rate the
fluorescence ascribed to the tryptophan species was
recorded (8–10). To this end, the skin sites of interest
were examined in vivo using a fluorescence spectro-
photometer (SPEX
SkinSkan, HORIBA Jobin Yvon
Inc., Edison, NJ) equipped with a Xenon arc light
source, double excitation and emission monochroma-
tors, and a bifurcated fiber-optic probe with a ran-
domized distribution between excitation and collection
fibers (diameter of each fiber: 200 lm). A detailed
description of the instrumentation is given elsewhere
(12). Before each set of measurements the instrument
was spectrally calibrated for excitation and emission in
the region 250–650 nm. The chromatic resolution of
the spectrofluorimeter was ±2 nm. Measurements
were performed by placing the fiber optic probe in
contact with the skin site of interest and recording the
excitation spectra in the range from 240 to 320 nm with
emission set at 340 nm (tryptophan excitation maxi-
mum at 295 nm). The tryptophan fluorescence signal
was normalized to the 390 nm excitation band to
minimize the effect of instrumental parameters on the
measurements (11).
Statistics
All data are presented as average ± one SE of mean
except otherwise noted. Comparisons between infant
and adult skin data were performed using Student’s
t-test where applicable and ANOVA test otherwise.
Statistical significance was accepted at the level of
p<0.01.
RESULTS
Infant Skin Surface Is Different than Adult
Both video microscopy and CLSM images demonstrated
striking differences between adult and infant skin surface
(Fig. 1). In infants, the network of microrelief grooves
appearstobedenser(morelines per projected area) and
the intra-relief ‘‘island’’ structures appear to be more
rounded and plump. In contrast, these structures in
adults appear to be flatter and with larger surface area.
Moreover, in adults, the edges of these structures are
more distinct in video microscopy images. This increase
in contrast may be attributed to the dryer condition of the
corneocytes at these sites. Infant skin on the other hand
appears to be well hydrated in accordance with the skin
moisturization measurements previously reported (3).
Surprisingly, the depth of the glyphics as measured in the
CLSM images was found to be the same in adult and
infant skin (90 lm).
Infant Skin Architecture Is Different than Adult
Beneath the Surface
In vivo CLSM images revealed differences between adult
and infant epidermis (Fig. 2). The projected area of
Figure 1. The skin surface appears different between infants
and adults. Examples are shown of in vivo video microscopy
and confocal laser scanning microscopy images of the sur-
face of infant and adult skin. Infant skin appears to have a
denser network of microrelief lines than adult skin. The stra-
tum corneum ‘‘island’’ structures are flatter and larger in adult
skin.
Stamatas et al: Infant Skin Microstructure In Vivo 127
dermal papillae displays a fairly homogeneous size dis-
tribution in infant skin, whereas in adults, the dermal
papillae vary in size and are more irregular in shape.
Interestingly, in infant skin, there appears to be a one-
to-one relationship between the intra-glyph ‘‘island’’
structures at the surface and the underlying dermal
papillae at the bottom of the epidermis, possibly
indicating a single structural unit relationship. This
relationship is absent in adult skin, where a single surface
‘‘island’’ may correspond to several papillae underneath.
Infant SC and Supra-Papillary Epidermis Are Thinner
than Adult
Infant SC thickness calculated from in vivo CLSM
images is on average 30% lower than that of adult,
whereas the infant supra-papillary epidermis was found
to be on average 20% thinner than that of adults
(Table 1).
Infant Corneocytes and Granular Layer Keratinocytes
Are Smaller than Adult
Corneocyte size was evaluated by image analysis of
adhesive tapes removed from the skin sites of interest
(Fig. 3). In all sites examined (upper inner arm, dorsal
forearm, and lower thigh), the size of infant corneocytes
was found to be smaller than that of adult (Table 1). No
differences were noticed in corneocyte size among the
three sites examined for either adults or infants. The
differences between adult and infant keratinocyte size
were measurable to a lesser but still significant level at the
granular layer (Fig. 4, Table 1). Interestingly, both
infant and adult keratinocytes undergo on average a
doubling of their projected area as they transform from
granular cells to corneocytes. Cell densities in the gran-
ular (but not the corneal) layer could also be measured
form the confocal data and are shown in Table 1. The
smaller cell size in infants is often thought to be due to
higher cell turnover rates. We confirmed that this is the
case using in vivo fluorescence spectroscopy (Fig. 5).
These data also show that there appears to be a pro-
gressive decrease in the epidermal cell proliferation rate
during the first year of life.
The Border Between Papillary and Reticular Dermis
May Be Observed in Adults
Confocal laser scanning microscopy reflectance intensity
profiles decrease in an exponential-like manner because
of light losses by scattering. In the case of adult skin, the
monotonic decay is interrupted by a local plateau at
around 100–140 lm, which is absent in the profiles of
infant skin (Fig. 6). This plateau has previously been
ascribed to the border between papillary and reticular
dermis (13). Collagen and elastic fibers in the reticular
Figure 2. In vivo confocal laser scanning microscopy reveals differences between adult and infant skin beneath the skin surface.
Representative images are shown of different layers through the skin. The one-to-one relationship of the papillae to the stratum
corneum surface structures is evident in infant skin and not in adult. Also the overall brighter signal at the collagen level in adult
skin is characteristic of thicker collagen fibers in adult skin.
TABLE 1. Comparison of structural parameters between infant
and adult skin. The stratum corneum and supra-papillary epi-
dermis are thinner in infant skin compared to adult skin. Infant
corneocytes are smaller than adult in all three areas where sam-
ples were collected (upper inner arm, dorsal forearm, and upper
thigh area). Infant cell at the granular layer are smaller compared
to adult. Infant cell density at the granular layer is higher than
adult. All differences between infants and adults are statistically
significant. Data are shown as average ± one standard deviation
Infant skin Adult skin
Stratum corneum
thickness (lm)
7.3 ± 1.1 10.5 ± 2.1
Supra-papillary epidermal
thickness (lm)
29.7 ± 3.4 36.2 ± 5.2
Corneocyte size (lm
2
)
Upper inner arm 949.9 ± 19.1 1077.6 ± 26.9
Dorsal forearm 907.3 ± 23.4 1071.0 ± 25.7
Thigh 953.0 ± 23.8 1154.4 ± 33.7
Granular cell size (lm
2
) 443.6 ± 6.2 475.9 ± 8.3
Granular cell density
(cells mm
2
)
1577.8 ± 45.4 1382.6 ± 37.4
128 Pediatric Dermatology Vol. 27 No. 2 March April 2010
dermis are thicker than those of the papillary layer
and are expected to increase locally the reflected signal.
This feature was absent in the data from infant skin,
confirming the published observation that the collagen
bundles of the upper reticular dermis are not as thick in
infants as in adults (14,15) and therefore the transition
between papillary and reticular dermis is more gradual in
infants. Note that the small shoulders present in the in-
fant data are attributed to noise.
DISCUSSION
During the first year of life, skin has been shown to be in
a state of active development, in particular with regard to
its water handling properties (3,15–17). Such functional
differences between infant and adult skin may arise at
least in part from differences in microstructure. In this
study, we examined the morphology of infant and adult
skin in vivo at the microscopic level. We observed
differences in microglyph density, cell size, epidermal
layer thickness, dermal structure, and density of papillae.
On the other hand, some striking similarities exist, as for
example, the glyphic structures perceived on the surface
of the SC have the same depth in infant and adult skin.
Moreover, we report for the first time a structural rela-
tionship between papillae and skin surface that exists in
infant skin and disappears later in life.
In utero epidermal maturation occurs continuously.
Functional maturation of the SC begins in the third
trimester of gestation. By 34-weeks gestational age the
epidermis has largely matured: the SC and the dermo-
epidermal undulations become visible (18). However,
skin structures at the organ level continue to evolve even
after birth. During the first 3 months of life, skin
roughness decreases correlating with a concomitant
increase in SC hydration (19), although this may not be
Figure 3. Infant corneocytes are smaller than the adult ones.
Representative video microscopy images of corneocytes re-
moved by tape stripping from infant and adult skin.
Figure 4. Infant granular cells are smaller than the adult
ones. Representative confocal laser scanning microscopy
images at the depth where granular cells can be observed
from infant and adult skin.
Figure 5. The epidermal cell proliferation rate in infants is
higher than adults. The intensity of the tryptophan band
(295 nm excitation) was measured using in vivo fluorescence
excitation spectroscopy. The star (*) indicates statistical sig-
nificance between this infant group and the adult group.
Figure 6. Confocal laser scanning microscopy shows that
the border between papillary and reticular dermis (shoulder
between 90 and 140 lm depth) can be observed in adult skin,
but is absent in baby skin. The gray level intensity profiles for
the confocal stacks are given as average values normalized
to the laser power used at the corresponding depth. Data are
given as mean ± one SD.
Stamatas et al: Infant Skin Microstructure In Vivo 129
the only reason. Moreover, scanning electron micros-
copy revealed 10 times more hair structures per unit skin
surface area in newborns compared with adults (20).
Infant corneocytes have been reported to be thicker
(in height) than adult (21). The size of corneocytes shed
from the horny layer has been suggested as an indication
of the proliferation rate of the epidermal keratinocytes:
smaller size indicating faster proliferation (22). Detailed
three-dimensional morphometry using atomic force
microscopy showed that although adult corneocytes are
flatter than infant, the total volume remains statistically
similar between the two groups (21). In accordance with
these reports, our data also illustrate that the infant
corneocyte, as well as granular keratinocyte, projected
area is smaller than the adult and we confirm the higher
proliferation rate in infants using an intrinsic fluores-
cence marker of epidermal cell proliferation (9).
It has been reported that morphologically there is
increasing epidermal cellularity and undulation of the
rete ridges at the dermo-epidermal junction in neonates
and young infants (18). Our data corroborate these
results. Beyond these observations, we observed in in-
fants a direct relationship between the dermal papillae
structures at the bottom of the epidermis and the intra-
relief areas of SC at the surface. There appears to be a
structural unit in infant epidermis that potentially points
to a common precursor proliferative unit at the basal
layer. This one-to-one relationship between epidermal
structures is lost in adults possibly implicating both
chronological aging and photoaging processes. Alterna-
tively, the loss of the one-to-one relationship in a growing
organism may develop with the original epidermal units
controlling a greater area with more dermal papillae.
No consensus in the literature for the comparison in
terms of skin thickness between infants and adults was
observed. While a pulsed ultrasound study showed that
infant skin is thinner than adult skin (23) and a second
study showed that there was a slight increase in the
number of SC layers with age in the skin of the cheek and
back (24), another report stated that the thickness of their
SC is not significantly different and therefore cannot be
used to explain differences in percutaneous absorption
(25). Such discrepancies may be attributed to variations
in histological preparations. Ex vivo SC can have very
different appearance particularly when prepared for
histology. Using in vivo methods, we show that both the
SC and the supra-papillary epidermis are thinner in
infant skin compared with adult. Furthermore, the SC
thickness calculated in this study for adult subjects is
within the range of reported thicknesses calculated from
in vivo CLSM data: 8–14 lm depending on body site (5).
Histometric measurements by in vivo CLSM com-
prise a sensitive and noninvasive tool for characterizing
and quantifying histological changes in the epidermis
and papillary dermis as a result of aging (26). Age-related
effects on epidermal structures have been studied in
adults using noninvasive in vivo methods such as
ultrasound [for a review see (27)], optical coherence
tomography (OCT) (13,28), and CLSM (13,26). Ultra-
sonography has been reportedtogivevariableresults
concerning the measurement of skin thickness (27) and
the only parameter that can be extracted from OCT is
equivalent to a similar parameter measured from CLSM
image analysis (13). Therefore of the three in vivo
methods, more information can be obtained from
CLSM, which is taking the place of a ‘‘golden standard’’
for in vivo micro-structural measurements.
Skin surface morphology has long been recognized as
reflecting skin pathology. In a study on hairless mice,
skin surface roughness was found to be associated with
both water content and thickness of SC (29). Infant
micro-relief lines were found to be denser than adult,
which implies a larger surface per projected area.This in
turn may explain at least in part the differences between
infant and adults skin in terms of water absorption and
desorption (3).
Moreover, although infant SC has higher TEWL
rates than adult, it also has higher water content as
shown both by capacitance measurements and by in vivo
Raman microspectroscopy (3). This is not necessarily a
contradiction as TEWL values can be independent of the
water content of the SC reservoir as long as the influx-
outflux equilibrium of water in the SC can support the
high values of water content. Interestingly, the plateau
level in the water concentration profile calculated by the
Raman method (marking the beginning of viable epi-
dermis) is reached 5–10 lmearlierininfantSCthanin
adult. This observation confirms the finding of the current
study that infant SC is thinner, keeping in mind that cross
study comparisons should be made with caution.
In conclusion, infant skin continues to change and
develop during the first years of life. We report that
compared with adult skin, infant microrelief structures
are denser, SC and supra-papillary dermis are thinner,
dermal papilla size is more uniform, corneocyte and
granular cell size are smaller. In addition, we observed a
one-to-one relationship between papillae and surface
structures in infant skin exclusively and a distinct papil-
lary-to-reticular dermis transition in adult skin only.
Previous reports on differences in skin thickness, skin
pH, and SC hydration levels between newborn and adult
skin show that neonatal skin is always adjusting to the
extra-uterine environment (1). In the light of the findings
of this article as well as our previous report (3), we can
extend the above statement to infants through at least
theirfirstyearoflife.
130 Pediatric Dermatology Vol. 27 No. 2 March April 2010
ACKNOWLEDGMENTS
The authors would like to acknowledge the contribution
of Melissa Chu, Ashley Winter, and Fanny Le Goff
for their help in the corneocyte and granular cell size
analysis.
CONFLICT OF INTEREST
All authors are employees of the Johnson & Johnson
family of companies as indicated by their affiliations.
REFERENCES
1. Chiou YB, Blume-Peytavi U. Stratum corneum matura-
tion. A review of neonatal skin function. Skin Pharmacol
Physiol 2004;17:57–66.
2. Mancini AJ, Kaulback K, Chamlin SL. The socioeco-
nomic impact of atopic dermatitis in the United States: a
systematic review. Pediatr Dermatol 2008;25:1–6.
3.NikolovskiJ,StamatasGN,KolliasNetal.Barrier
function and water-holding and transport properties of
infant stratum corneum are different from adult and
continue to develop through the first year of life. J Invest
Dermatol 2008;128:1728–1736.
4. Selkin B, Rajadhyaksha M, Gonzalez S et al. In vivo
confocal microscopy in dermatology. Dermatol Clin
2001;19:369–377.
5. Huzaira M, Rius F, Rajadhyaksha M et al. Topographic
variations in normal skin, as viewed by in vivo reflectance
confocal microscopy. J Invest Dermatol 2001;116:846–852.
6. Gonzalez S, Swindells K, Rajadhyaksha M et al. Changing
paradigms in dermatology: confocal microscopy in clinical
and surgical dermatology. Clin Dermatol 2003;21:359–
369.
7. Branzan AL, Landthaler M, Szeimies RM. In vivo
confocal scanning laser microscopy in dermatology. Lasers
Med Sci 2007;22:73–82.
8. Brancaleon L, Lin G, Kollias N. The in vivo fluorescence
of tryptophan moieties in human skin increases with UV
exposure and is a marker for epidermal proliferation.
J Invest Dermatol 1999;113:977–982.
9. Doukas AG, Soukos NS, Babusis S et al. Fluorescence
excitation spectroscopy for the measurement of epidermal
proliferation. Photochem Photobiol 2001;74:96–102.
10. Kollias N, Gillies R, Moran M et al. Endogenous skin
fluorescence includes bands that may serve as quantitative
markers of aging and photoaging. J Invest Dermatol
1998;111:776–780.
11. Stamatas GN, Estanislao RB, Suero M et al. Facial skin
fluorescence as a marker of the skin’s response to chronic
environmental insults and its dependence on age. Br J
Dermatol 2006;154:125–132.
12. Stamatas GN, Wu J, Kollias N. Non-invasive method for
quantitative evaluation of exogenous compound deposi-
tion on skin. J Invest Dermatol 2002;118:295–302.
13. Neerken S, Lucassen GW, Bisschop MA et al. Character-
ization of age-related effects in human skin: a comparative
study that applies confocal laser scanning microscopy and
optical coherence tomography. J Biomed Opt 2004;9:274–
281.
14. Vitellaro-Zuccarello L, Cappelletti S, Dal Pozzo Rossi V
et al. Stereological analysis of collagen and elastic fibers in
the normal human dermis: variability with age, sex, and
body region. Anat Rec 1994;238:153–162.
15. Holbrook KA. A histological comparison of infant and
adult skin. New York: Marcel Dekker, Inc., 1982.
16. Visscher MO, Chatterjee R, Munson KA et al. Changes in
diapered and nondiapered infant skin over the first month
of life. Pediatr Dermatol 2000;17:45–51.
17. Visscher MO, Chatterjee R, Ebel JP et al. Biomedical
assessment and instrumental evaluation of healthy infant
skin. Pediatr Dermatol 2002;19:473–481.
18. Evans NJ, Rutter N. Development of the epidermis in the
newborn. Biol Neonate 1986;49:74–80.
19. Hoeger PH, Enzmann CC. Skin physiology of the neonate
and young infant: a prospective study of functional skin
parameters during early infancy. Pediatr Dermatol 2002;
19:256–262.
20. Marchini G, Nelson A, Edner J et al. Erythema toxicum
neonatorum is an innate immune response to commensal
microbes penetrated into the skin of the newborn infant.
Pediatr Res 2005;58:613–616.
21. Kashibuchi N, Hirai Y, O’Goshi K et al. Three-dimen-
sional analyses of individual corneocytes with atomic force
microscope: morphological changes related to age, location
and to the pathologic skin conditions. Skin Res Technol
2002;8:203–211.
22. Grove GL, Kligman AM. Corneocytes size as an indirect
measure of epidermal proliferative activity. In: Marks R,
Plewig G, eds. Stratum corneum. Berlin: Springer-Verlag,
1983:191–195.
23. Tan CY, Statham B, Marks R et al. Skin thickness
measurement by pulsed ultrasound: its reproducibility,
validation and variability. Br J Dermatol 1982;106:657–
667.
24. Ya-Xian Z, Suetake T, Tagami H. Number of cell layers of
the stratum corneum in normal skin – relationship to the
anatomical location on the body, age, sex and physical
parameters. Arch Dermatol Res 1999;291:555–559.
25. Fairley JA, Rasmussen JE. Comparison of stratum
corneum thickness in children and adults. J Am Acad
Dermatol 1983;8:652–654.
26. Sauermann K, Clemann S, Jaspers S et al. Age related
changes of human skin investigated with histometric
measurements by confocal laser scanning microscopy in
vivo. Skin Res Technol 2002;8:52–56.
27. Waller JM, Maibach HI. Age and skin structure and
function, a quantitative approach (I): blood flow, pH,
thickness, and ultrasound echogenicity. Skin Res Technol
2005;11:221–235.
28. Gambichler T, Matip R, Moussa G et al. In vivo data of
epidermal thickness evaluated by optical coherence tomog-
raphy: effects of age, gender, skin type, and anatomic site.
J Dermatol Sci 2006;44:145–152.
29. Sato J, Yanai M, Hirao T et al. Water content and
thickness of the stratum corneum contribute to skin
surface morphology. Arch Dermatol Res 2000;292:412–
417.
Stamatas et al: Infant Skin Microstructure In Vivo 131
... Up to the first year of life, the level of NMF (natural moisturizing factor) is gradually growing, ensuring a better level of epidermis moisturization. The epidermis of newborns is about 50 µm thick, whereas in adults its can be up to 0.5 mm thick [1][2][3][4]. ...
... During the first months of life, the skin vascular network gradually develops to form the deep vascular plexus, upper vascular plexus, and capillary loops in dermal papillae. Small blood vessels in dermal papillae supply nutrients, oxygen, hormones, etc. to the epidermis [1,[3][4]6]. ...
... Therefore, the potential of concentrating collected substances in the tissue of infants and babies is significantly higher. The higher body surface to body mass ratio increases biological accessibility [1,[3][4][7][8]. ...
... As noted earlier, the skin turnover is driven by keratinocyte proliferation and maturation to corneocytes, followed by the desquamation process. Stamatas et al. (2010) performed an in vivo study regarding the microstructure and proliferation of epidermal cells in infants compared with adults [36]. Three different sites were examined, namely the inner arm, dorsal forearm, and lower thigh. ...
... As noted earlier, the skin turnover is driven by keratinocyte proliferation and maturation to corneocytes, followed by the desquamation process. Stamatas et al. (2010) performed an in vivo study regarding the microstructure and proliferation of epidermal cells in infants compared with adults [36]. Three different sites were examined, namely the inner arm, dorsal forearm, and lower thigh. ...
... The fluorescence of tryptophan, with an excitation wavelength of 295 nm, was used as the marker of epidermal cell proliferation. The findings showed that the size of corneocytes in infants was significantly smaller compared with that of adults (p < 0.05) [36]. The rate of epidermal cell proliferation in newborns and infants aged up to 3 months was higher than that of older infants and adults (p < 0.05) [36]. ...
Article
Full-text available
A good understanding of infant skin should provide a rationale for optimum management of the health of this integument. In this review, we discuss the skin barrier function of infants, particularly with reference to the use of diapers and baby wipes. The skin barrier of newborns continues to develop with age. Two years after birth, the barrier properties of infant skin closely resemble those of adult skin. However, several risk factors may contribute to impaired skin barrier and altered skin permeability in infants. Problems may arise from the use of diapers and baby wipes. The skin covered by a diaper is effectively an occluded environment, and thus is vulnerable to over-hydration. To date there has been no published information regarding dermal absorption of ingredients contained in baby wipes. Similarly, dermal absorption of topical ingredients in infants with underlying skin conditions has not been widely explored. Clearly, there are serious ethical concerns related to conducting skin permeation studies on infant skin. However, the increasing availability of non-invasive methods for in vivo studies is encouraging and offers new directions for studying this important patient group.
... The viable epidermis is distinct from the SC, as it contains nucleated keratinocytes, melanocytes, Langerhans cells, and Merkel cells [35]. Some investigations of epidermis thickness in children include SC thickness and identify it as the supra-papillary epidermis or epidermis thickness [36][37][38]. Of the 17 articles, only eight specifically measured SC thickness in children compared to adults. ...
... Of the 17 articles, only eight specifically measured SC thickness in children compared to adults. The body areas in which SC thickness was most often measured in children were the forearms, upper arm, and abdomen [21,[36][37][38][39][40], although data from other body areas such as the buttocks and thighs have also been collected [36][37][38]40]. Measurements of histological skin samples ex vivo and confocal microscopy in vivo were the most common methods used to measure skin thickness. ...
... Of the 17 articles, only eight specifically measured SC thickness in children compared to adults. The body areas in which SC thickness was most often measured in children were the forearms, upper arm, and abdomen [21,[36][37][38][39][40], although data from other body areas such as the buttocks and thighs have also been collected [36][37][38]40]. Measurements of histological skin samples ex vivo and confocal microscopy in vivo were the most common methods used to measure skin thickness. ...
Article
Full-text available
The higher skin surface area to body weight ratio in children and the prematurity of skin in neonates may lead to higher chemical exposure as compared to adults. The objectives of this study were: (i) to provide a comprehensive review of the age-dependent anatomical and physiological changes in pediatric skin, and (ii) to construct and evaluate an age-dependent pediatric dermal absorption model. A comprehensive review was conducted to gather data quantifying the differences in the anatomy and physiology of child and adult skin. Maturation functions were developed for model parameters that were found to be age-dependent. A pediatric dermal absorption model was constructed by updating a MoBi implementation of the Dancik et al. 2013 skin permeation model with these maturation functions. Using a workflow for adult-to-child model extrapolation, the predictive performance of the model was evaluated by comparing its predicted rates of flux of diamorphine, phenobarbital and buprenorphine against experimental observations using neonatal skin. For diamorphine and phenobarbital, the model provided reasonable predictions. The ratios of predicted:observed flux in neonates for diamorphine ranged from 0.55 to 1.40. For phenobarbital, the ratios ranged from 0.93 to 1.26. For buprenorphine, the model showed acceptable predictive performance. Overall, the physiologically based pediatric dermal absorption model demonstrated satisfactory prediction accuracy. The prediction of dermal absorption in neonates using a model-based approach will be useful for both drug development and human health risk assessment.
... Thus, considering that this new method can be performed in a non-invasive manner, it can be readily applied for children with immature skin structure and function. [20][21][22][23] In the present study, we further verified the applicability of the SSL-RNA method for the analysis of paediatric skin by comparing SSL-RNA profiles between children with AD showing mild-to-moderate AD and healthy children. Furthermore, the molecular pathology of paediatric AD was analysed. ...
Article
Full-text available
Background: Specimens for analysing the molecular pathology of skin disease are generally obtained through invasive methods, such as biopsy. However, less burdensome methods are desirable for paediatric patients. We recently established a method that comprehensively analyses RNA present in sebum (skin surface lipid-RNAs: SSL-RNAs) using a next-generation sequencer. Using this method, biological information can be obtained from the skin in a completely non-invasive manner. Objectives: To verify the applicability of the SSL-RNA method for analysis of paediatric skin and analyse the molecular pathology of mild-to-moderate atopic dermatitis (AD) in children. Methods: We collected sebum specimens from the whole faces of 23 healthy children and 16 children with mild-to-moderate AD (eczema area and severity index (EASI) score: 5.9 ± 2.6) ranging in age from 6 months to 5 years, using an oil-blotting film. We then extracted SSL-RNAs from the samples and performed an AmpliSeq transcriptomic analysis. Results: The expressions of genes related to keratinisation (LCE, PSORS1C2, IVL, and KRT17), triglyceride synthesis and storage (PLIN2, DGAT2, and CIDEA), wax synthesis (FAR2), ceramide synthesis (GBA2, SMPD3, and SPTLC3), antimicrobial peptides (DEFB1), and intercellular adhesion (CDSN), all of which are related to the skin barrier, are lower in children with AD than in healthy children. The children with AD also have higher expression of CCL17, a Th2-cytokine, and an increased Th2-immune response as demonstrated by a gene set variation analysis. Moreover, KRT17 and CCL17 expression levels are significantly correlated with the EASI score. Conclusions: Molecular changes associated with abnormal immune responses and the epidermal barrier in children with mild-to-moderate AD can be determined using the SSL-RNA method. This non-invasive method could therefore be a useful means for understanding the molecular pathology of paediatric AD.
Article
The prevalence of allergic diseases is on the rise, yet the environmental factors that contribute to this increase are still being elucidated. Laundry detergent (LD) that contains cytotoxic ingredients including microbial enzymes continuously comes into contact with the skin starting in infancy. An impaired skin barrier has been suggested as a route of allergic sensitization. We hypothesized that exposure of skin to LD damages the skin barrier resulting in systemic sensitization to allergens that enter through the impaired skin barrier. Mouse skin samples exposed in vitro to microbial proteases or LD exhibited physical damage, which was more pronounced in neonatal skin as compared to adult skin. Exposure of the skin to microbial proteases in vitro resulted in an increase in the levels of interleukin (IL)-33 and thymic stromal lymphopoietin (TSLP). BALB/c wild type mice epicutaneously exposed to LD and ovalbumin (OVA) showed an increase in levels of transepidermal water loss, serum OVA-specific immunoglobulin (Ig) G1 and IgE antibodies, and a local increase of Il33 , Tslp , Il4 and Il13 compared with LD or OVA alone. Following intranasal challenge with OVA, mice epicutaneously exposed to LD showed an increase in allergen-induced esophageal eosinophilia compared with LD or OVA alone. Collectively, these results suggest that LD may be an important factor that impairs the skin barrier and leads to allergen sensitization in early life, and therefore may have a role in the increase in allergic disease.
Article
Aim: Epicutaneous immunotherapy (EPIT) with peanut has been demonstrated to be safe but efficacy may be limited by allergen uptake through the skin barrier. To enhance allergen uptake into the skin, the authors used peanut-coated microneedles and compared them with EPIT in a peanut allergy mouse model. Methods: Sensitized mice were treated with peanut-coated microneedles or peanut-EPIT and then challenged with peanut to determine protection. Results: Treatment with peanut-coated microneedles was safe and showed enhanced desensitization to peanut compared with peanut-EPIT administered via a similar schedule. Protection was associated with reduced Th2 immune responses and mast cell accumulation in the intestine. Conclusion: Peanut-coated microneedles have the potential to present a safe method of improving allergen delivery for cutaneous immunotherapy.
Article
Objective To optimize the permethrin-based therapies for scabies infestations in infants and young children the efficacies of three different regimens were evaluated. Study design The retrospective analysis encompassed 85 infants and children aged <4 years with scabies. The children had received either topical permethrin 5% on the entire body on days 1/8 (I), on days 1/8/15 (II), on days 1/8/15 plus interim applications restricted to hands and feet on days 2/3/4//9/10/11 (III), or alternative treatments (IV). Results The intensified regimen, consisting of full-body permethrin applied on days 1/8/15 and hands/feet on days 2/3/4//9/10/11, resulted in cure of scabies in 73.5% of the cases. The cure rates were significantly higher compared with full-body permethrin given on days 1/8, which led to eradication in 44%, and were higher compared with the clearance in children who had received full-body permethrin on days 1/8/15 (53.8%) or alternative treatments (60%). For patients in whom permethrin had previously been applied, the intensified regimen resulted in eradication of scabies in 71.4% of the cases, compared with 30% and 55.6% after full-body permethrin on days 1/8 and 1/8/15, respectively. Conclusions The intensified regimen of full-body permethrin plus interim applications on hands/feet, which aims at reducing the number of mites present on the frequently heavily-infested palmoplantar sites in addition to the standard entire body application, appears efficacious in curing scabies in young children.
Article
Atopic dermatitis (AD) is the most prevalent skin disease in the early childhood and is a considerable problem both for patients and members of their families and for the society on the whole. In most cases, AD requires a long-term therapy such as the use of anti-inflammatory drugs. Selective inhibitors of the synthesis and release of proinflammatory cytokines - topical calcineurin inhibitors (Tcis) - are now used to solve this problem, with pimecrolimus being one of them. Pimecrolimus has been thoroughly examined for the past decade in different clinical studies involving a total of over 4,000 infants (below 2 years of age). These studies demonstrated the efficacy and safety of pimecrolimus for AD in children provided it is used in a long-term therapy on an intermittent basis. Unlike topical corticosteroids, the long-term use of pimecrolimus is not associated with any risk of development of systemic immunosuppression, skin atrophy, skin barrier dysfunction or systemic absorption so it is safe even if applied to the most sensitive skin areas. In view of this, the authors make a conclusion that pimecrolimus used in the form of a cream is a safe and efficient drug for the treatment of infants aged over three months suffering from atopic dermatitis.
Preprint
Full-text available
Purpose: This study aimed to evaluate whether bathing newborns within 36 hours after birth has a temporary negative impact on skin barrier metrics and relates to atopic dermatitis (AD) development. Methods: 55 newborns were bathed with water at 24-36 hours after birth, while 102 newborns did not have bath. Skin barrier metrics, including facial and underarm transepidermal water loss (TEWL), stratum corneum hydration (SCH), and skin humidity, were evaluated 1 hour before and after bath (T0 and T1, respectively), as well as on the next day (T2). A follow-up questionnaire via telephone was conducted 12-month later (T3). AD screening was determined based on the questionnaire. Results: In the non-bathed newborns, no significant alteration in skin barrier function was observed. In the bathed newborns, the underarm SCH significantly deteriorated from 16.60±21.74 at T0 to 8.16±12.27 at T2 (51% deterioration, p=0.009). Deteriorations were also observed for the facial and underarm humidity right after bath (-5%, p=0.017 and -4%, p=0.012) as well as on the next day (-6%, p=0.003 and -5%, p=0.001). At T3, 5% non-bathed newborns were determined to have developed AD during the past 12-month, while this number increased by 4-fold (21%) in the bathed newborns (p=0.010). Conclusion: This study demonstrated a temporary negative impact on newborn’s skin barrier function caused by bathing within 36 hours after birth. Deteriorated skin barrier function in the temporary window may still leave the newborn susceptible to infection and allergy, increasing the risk of triggering AD onset.
Article
Fluorescence excitation spectroscopy was used to assess cellular turnover in human skin by monitoring changes of endogenous fluorescence. Epidermal proliferation was induced with α‐hydroxy acids. Commercially available glycolic acid creams (8 and 4% wt/wt concentration) and a vehicle cream (placebo) were applied in a randomized double blinded fashion on subjects' forearms, twice daily for 21 days. Excitation spectra were recorded (excitation 250–360 nm, emission 380 nm) at days 0, 1, 3, 7, 10, 11, 14, 17 and 21. The 295 nm excitation band (assigned to tryptophan moieties) was used in this study as a marker for cellular proliferation. To further reduce the day‐to‐day variability of the skin fluorescence the intensity of the 295 nm band was normalized to the 334 nm band (assigned to collagen crosslinks). The fluorescence emission intensity from placebo‐treated skin remained practically unchanged over the period of the measurements while the fluorescence intensity measured from the glycolic acid–treated skin increased monotonically with treatment. The rate of increase of the excitation intensity with treatment was found to be dose dependent. The epidermal 295 nm band may be used as a quantitative marker to monitor the rate of proliferation of epidermal keratinocytes noninvasively.
Chapter
Since horny cells are continually being shed from the skin surface, it is a relatively simple matter to collect these corneocytes without harm or inconvenience to the donor and to examine them in a variety of ways. A great deal of information can be obtained about the structure and function of the stratum corneum and the underlying viable epidermis by using these exfoliative cytological procedures [4, 5, 8].
Article
Time- and site-dependent differences in epidermal barrier properties were investigated over the first 28 days of life in healthy term newborn infants. Diapered and nondiapered skin sites were contrasted to the volar forearm of adults (mothers). Thirty-one term infants were evaluated in the hospital on postnatal day 1 and at home on days 4, 7, 14, 21, and 28 for a total of six visits. Measurements included baseline skin hydration, continuous capacitive reactance, peak water sorption, rate of water desorption, skin pH, skin temperature, and environmental conditions. Changes in epidermal barrier properties over the first 4 weeks of life included an increase in surface hydration, a decrease in transepidermal water movement under occlusion, a decrease in surface water desorption rate, and a decrease in surface pH. Diapered and nondiapered regions were indistinguishable at birth but exhibited differential behavior over the first 14 days, with the diapered region showing a higher pH and increased hydration. Maternal measurements remained constant throughout the period. We conclude that healthy newborn skin undergoes progressive changes in epidermal barrier properties over the first 28 days. Adult skin testing does not replicate newborn skin during the first month of life.
Article
Histological development of the epidermis was studied on skin samples from 169 infants (gestation 24-40 weeks, age up to 1 year). Gestation markedly influenced epidermal development. Before 30 weeks, the epidermis is thin, has few cell layers and a poorly formed stratum corneum, but by 34 weeks it has largely matured. Postnatal influence on epidermal development is marked in the preterm infant, so that histologically the epidermis of the most immature infant resembles that of a term infant by 2 weeks of age. These changes in histology exactly parallel the development of the barrier properties of newborn skin.
Article
We compared the thickness of the stratum corneum from abdominal skin in infants less than 3 months of age, children between 3 months and 11 years, and adults. Measurements were made with a filar micrometer eyepiece on histologic sections obtained at autopsy. No significant differences were seen; therefore, a stratum corneum of different thickness cannot be used to explain differences in percutaneous absorption, supporting previous work which suggested that term infants and children have an efficient skin barrier. The greater toxicity from percutaneous absorption of topical compounds sometimes seen in children is more likely due to their increased surface to volume ratio and/or metabolic differences.
Article
The reproducibility of the pulsed ultrasound technique for the determination of skin thickness was investigated, using two independent observers. No systematic difference was found and a high correlation was obtained. Studies were also undertaken to validate the pulsed ultrasound technique as a measure of true skin thickness. Skin thickness determined in vitro was found to be greater than when in vivo determinations were made by either the pulsed ultrasound or a xeroradiographic technique, probably due to the release of in vivo tension within the dermis after excision. Skin thickness was found to increase linearly with age up to the age of 20 years and to decrease linearly with age subsequently. Differences in skin thickness between the sexes and in different sites of the body were demonstrated.
Article
Normal human dermis has been analyzed using stereological methods to estimate the quantitative modifications of collagen and elastic fibers in relation to age, sex, and body region. Forty-five skin biopsies from the trunk or the limbs of 26 males and 19 females of different age were fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin. The relative volumes of collagen and elastic fibers were calculated by the point counting method on 1 micron semithin sections. Photographic sampling was performed on four consecutive dermis layers: the papillary layer and three consecutive layers of reticular dermis. The data were subjected to analysis of variance which showed that all the factors studied exert a significant influence on the relative amounts of collagen and elastic fibers. The fractional volume of collagen fibers is constant throughout all dermis layers analyzed and is always higher in females than in males, except for the second and third decades of life. Collagen fiber density increases with age in both sexes up to 30-40 years, when it starts decreasing. Both the relative volumes and the diameters of elastic fibers increase from papillary to deep reticular dermis. In reticular dermis of both sexes there is an increment of elastic fiber density in the first decade of life, followed by a drop particularly marked in males. After 20 years, the relative volume of elastic fibers displays a decreasing trend in females, whereas it increases in males, attaining the highest values beyond the 40s.
Article
Aging and photoaging cause distinct changes in skin cells and extracellular matrix. Changes in hairless mouse skin as a function of age and chronic UVB exposure were investigated by fluorescence excitation spectroscopy. Fluorescence excitation spectra were measured in vivo, on heat-separated epidermis and dermis, and on extracts of mouse skin to characterize the absorption spectra of the emitting chromophores. Fluorescence excitation spectra obtained in vivo on 6 wk old mouse skin had maxima at 295, 340, and 360 nm; the 295 nm band was the dominant band. Using heat separated tissue, the 295 nm band predominantly originated in the epidermis and the bands at 340 and 360 nm originated in the dermis. The 295 nm band was assigned to tryptophan fluorescence, the 340 nm band to pepsin digestable collagen cross-links fluorescence and the 360 nm band to collagenase digestable collagen cross-links fluorescence. Fluorescence excitation maxima remained unchanged in chronologically aged mice (34-38 wk old), whereas the 295 nm band decreased in intensity with age and the 340 nm band increased in intensity with age. In contrast, fluorescence excitation spectra of chronically UVB exposed mice showed a large increase in the 295 nm band compared with age-matched controls and the bands at 340 and 350 nm were no longer distinct. Two new bands appeared in the chronically exposed mice at 270 nm and at 305 nm. These reproducible changes in skin autofluorescence suggest that aging causes predictable alterations in both epidermal and dermal fluorescence, whereas chronic UV exposure induces the appearance of new fluorphores.
Article
We counted the number of cell layers in the stratum corneum (SC) of normal skin taken from different anatomical locations of the body of 301 individuals of various ages. Frozen 6 microm thick sections were stained with a 1% aqueous solution of safranin and observed under a microscope after application of 2% KOH solution. There were great variations in the number of SC cell layers (mean +/- SD) according to location and among different individuals. The smallest number was found in genital skin (6 +/- 2), followed in order by skin of the face (9 +/- 2), neck (10 +/- 2), scalp (12 +/- 2), trunk (13 +/- 4), extremities (15 +/- 4) and the palms and soles (47 +/- 24). The heel showed the largest number (86 +/- 36). No definite correlation was found between the number of corneocyte layers and sex of the individual, whereas there was a slight increase in the number of SC layers with age in the skin of the cheek and back, particularly in male individuals. Comparison of these data with those from functional assessments of the SC of the skin from various locations of healthy adults showed that transepidermal water loss, an indicator of SC barrier function, reflected the number of corneocyte cell layers. In contrast, high-frequency conductance, an indicator of the hydration state of the outer SC, did not seem to be under the influence simply of the number of SC cell layers.