Number Of Epidermal Cell Layers Research Articles

Potential inhibition of 12-O-tetradecanoylphorbol-13-acetate-induced inflammation, hyperproliferation, and hyperplasiogenic responses by celecoxib in mouse skin

Purpose Skin exposure to noxious agents leads to cutaneous lesion marked by an increase in inflammation, cellular proliferation, and hyperplasiogenic reactions. Studies have demonstrated that these damages breach the skin integrity resulting in the aetiology of various cutaneous disorders like atopic dermatitis, eczema, psoriasis, and development of non-melanoma skin cancer. Celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, is an effective treatment for a variety of inflammatory diseases. Its importance in the therapy of skin problems, however, remains under appreciated. Methods We tested efficacy of topically applied celecoxib in mitigating skin inflammation, cellular proliferation, and hyperplasia induced by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) in Swiss albino mice. Results Celecoxib (5 and 10 μmol) markedly reduced TPA (10 nmol) induced prostaglandin E2 (PGE2) production, oedema formation, myeloperoxidase (MPO) activity, and levels of pro-inflammatory cytokines such as tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6). It also resulted in a considerable decrease in ornithine decarboxylase (ODC) activity and the incorporation of [3H]-thymidine into DNA. In addition, there was a significant reduction in histoarchitectural abnormalities such as epidermal thickness, number of epidermal cell layers, neutrophil infiltration, intercellular oedema, and vasodilation. Conclusion Our results demonstrate that topical celecoxib can reduce the inflammation, hyperproliferation, and hyperplasiogenic events of skin insults suggesting that it may prove to be a valuable management option for cutaneous lesion and associated illnesses such as atopic dermatitis, eczema, and psoriasis, as well as the emergence of non-melanoma cancer.

A gibberellin-deficient maize mutant exhibits altered plant height, stem strength and drought tolerance.

The reduction in endogenous gibberellin improved drought resistance, but decreased cellulose and lignin contents, which made the mutant prone to lodging. It is well known that gibberellin (GA) is a hormone that plays a vital role in plant growth and development. In recent years, a growing number of studies have found that gibberellin plays an important role in regulating the plant height, stem length, and stressed growth surfaces. In this study, a dwarf maize mutant was screened from an EMS-induced mutant library of maize B73. The mutated gene was identified as KS, which encodes an ent-kaurene synthase (KS) enzyme functioning in the early biosynthesis of GA. The mutant was named as ks3-1. A significant decrease in endogenous GA levels was verified in ks3-1. A significantly decreased stem strength of ks3-1, compared with that of wild-type B73, was found. Significant decreases in the cellulose and lignin contents, as well as the number of epidermal cell layers, were further characterized in ks3-1. The expression levels of genes responsible for cellulose and lignin biosynthesis were induced by exogenous GA treatment. Under drought stress conditions, the survival rate of ks3-1 was significantly higher than that of the wild-type B73. The survival rates of both wild-type B73 and ks3-1 decreased significantly after exogenous GA treatment. In conclusion, we summarized that a decreased level of GA in ks3-1 caused a decreased plant height, a decreased stem strength as a result of cell wall defects, and an increased drought tolerance. Our results shed light on the importance of GA and GA-defective mutants in the genetic improvement of maize and breeding maize varieties.

Interactions of donor sources and media influence the histo-morphological quality of full-thickness skin models.

Human artificial skin models are increasingly employed as non-animal test platforms for research and medical purposes. However, the overall histopathological quality of such models may vary significantly. Therefore, the effects of manufacturing protocols and donor sources on the quality of skin models built-up from fibroblasts and keratinocytes derived from juvenile foreskins is studied. Histo-morphological parameters such as epidermal thickness, number of epidermal cell layers, dermal thickness, dermo-epidermal adhesion and absence of cellular nuclei in the corneal layer are obtained and scored accordingly. In total, 144 full-thickness skin models derived from 16 different donors, built-up in triplicates using three different culture conditions were successfully generated. In univariate analysis both media and donor age affected the quality of skin models significantly. Both parameters remained statistically significant in multivariate analyses. Performing general linear model analyses we could show that individual medium-donor-interactions influence the quality. These observations suggest that the optimal choice of media may differ from donor to donor and coincides with findings where significant inter-individual variations of growth rates in keratinocytes and fibroblasts have been described. Thus, the consideration of individual medium-donor-interactions may improve the overall quality of human organ models thereby forming a reproducible test platform for sophisticated clinical research.

Morphological Studies on the Inhibitory Effects of Photoaging Skin of Fermented Red Ginseng in Hairless Mice

To investigate the anti-photoaging effect of fermented Red Ginseng(RG) in SKH-1 mice. We examined the effects of extracts of non-fermented RG(NRG group), fermented RG(FRG group) and fortified fermented RG(FFRG group) on skin wrinkles formation, histological changes related to the number of epidermal cell layers, epidermal thickness, neutrophil infiltration into dermis, degradation of collagen fibers, and the number of mast cells, and immunohistochemical changes related to cytokines and enzymes in photoaging skin caused by UVB irradiation of SKH-1 mice. The oral administration(300 ㎎/㎏ B.W./day) and topical application(100 ㎕/mouse/day) of extracts of NRG, FRG and FFRG inhibited increases in epidermal thickness and wrinkle formation compared to control group in dorsal skin induced by UVB irradiation. We observed more increased stainability of acid fuschin and aniline blue in dermis of FFRG group than those of other groups. Furthermore, NRG, FRG and FFRG prevented the disruption of collagen fibers within papillary layer of dermis, and decreased number of mast cells in the dorsal skins induced by UVB irradiation. We observed fine wrinkle formation in FFRG group. Treatment with NRG, FRG and FFRG decreased immunohistochemical density of myeloperoxidase related to inflammation in the photoaging skin. We observed more decreased immunohistochemical density of myeloperoxidase in FFRG group than those of other groups. Immunohistochemical density of PCNA and Ki-67 in FFRG group was more decreased than those of other groups. Our study suggests that fermented red ginseng extracts participates in inhibitory effects in the morphological processes related to photoaging skin on UVB irradiated SKH-1 mice.

Photochemoprotective Effect of Calluna vulgaris Extract on Skin Exposed to Multiple Doses of Ultraviolet B in SKH-1 Hairless Mice

UVB is a major cause of nonmelanoma skin cancer in humans. Photochemoprevention represents an important strategy in protecting the skin against the detrimental effects of ultraviolet B (UVB). We investigated the activity of Calluna vulgaris (Cv) delivered via a hydrogel on 3 main pathways (oxidative stress, inflammation, DNA damage) on skin exposed to multiple doses of UVB in SKH-1 mice. Fifty female mice were divided randomly into 5 groups: control, vehicle, UVB irradiated, Cv + UVB irradiated, and Cv + vehicle + UVB irradiated. The extract was applied topically on the skin in a dose of 4 mg polyphenols/cm2 30 minutes before each UVB (240 mJ/cm2) exposure over 10 consecutive days. Malondialdehyde, reduced glutathione, tumor necrosis factor-α, interleukin-6, cyclobutane pyrimidine dimer (CPD) levels, sunburn cell formation and epidermal thickness, and the number of epidermal cell layers in skin were evaluated 24 hours after the last treatment. UVB increased cytokine levels (P < 0.001), formation of CPDs (P < 0.001) and sunburn cells (P < 0.001), and the epidermal thickness and number of epidermal cell layers (P < 0.001) compared with the control group. The topical application of Cv protected the skin against inflammation and DNA damage, as shown by a decreased number of CPDs (P < 0.001) and sunburn cells (P < 0.001). The administration of Cv via hydrogel may be a viable method for chemoprevention..

The Thyroid Hormone Receptors Modulate the Skin Response to Retinoids

BackgroundRetinoids play an important role in skin homeostasis and when administered topically cause skin hyperplasia, abnormal epidermal differentiation and inflammation. Thyroidal status in humans also influences skin morphology and function and we have recently shown that the thyroid hormone receptors (TRs) are required for a normal proliferative response to 12-O-tetradecanolyphorbol-13-acetate (TPA) in mice.Methodology/Principal findingsWe have compared the epidermal response of mice lacking the thyroid hormone receptor binding isoforms TRα1 and TRβ to retinoids and TPA. Reduced hyperplasia and a decreased number of proliferating cells in the basal layer in response to 9-cis-RA and TPA were found in the epidermis of TR-deficient mice. Nuclear levels of proteins important for cell proliferation were altered, and expression of keratins 5 and 6 was also reduced, concomitantly with the decreased number of epidermal cell layers. In control mice the retinoid (but not TPA) induced parakeratosis and diminished expression of keratin 10 and loricrin, markers of early and terminal epidermal differentiation, respectively. This reduction was more accentuated in the TR deficient animals, whereas they did not present parakeratosis. Therefore, TRs modulate both the proliferative response to retinoids and their inhibitory effects on skin differentiation. Reduced proliferation, which was reversed upon thyroxine treatment, was also found in hypothyroid mice, demonstrating that thyroid hormone binding to TRs is required for the normal response to retinoids. In addition, the mRNA levels of the pro-inflammatory cytokines TNFα and IL-6 and the chemotactic proteins S1008A and S1008B were significantly elevated in the skin of TR knock-out mice after TPA or 9-cis-RA treatment and immune cell infiltration was also enhanced.Conclusions/significanceSince retinoids are commonly used for the treatment of skin disorders, these results demonstrating that TRs regulate skin proliferation, differentiation and inflammation in response to these compounds could have not only physiological but also therapeutic implications.

Evaluation of beneficial and adverse effects of glucocorticoids on a newly developed full-thickness skin model

Glucocorticoids (GCs) are highly effective compounds widely used in the treatment of inflammatory diseases; however, they offer distinct adverse effects such as skin thinning in response to long-term topical treatment. Nevertheless it is difficult to deduce the safety of a newly synthesized compound from its structural formula. Efficient assay systems that measure beneficial and adverse effects are needed. In the present study the applicability of a three-dimensional full-thickness skin model (FTSM) is tested to display GC-induced effects regarding anti-inflammation and atrophy. It is shown that topical application of a commercial GC ointment suppresses the ultraviolet (UV)B induced induction of interleukin (IL)-6 and IL-8. Addition of purified betamethasone-17-valerate, prednicarbate and clobetasol-17-propionate to the culture medium for 14days caused a reduction in the number of epidermal cell-layers corresponding to the atrophic risk found in vivo. Similarly, repeated topical application of five GC creams induced epidermal thinning. Evidence is given that the inhibitory effect on keratinocyte proliferation contributes to this effect. Furthermore, dermal thinning was monitored by measuring type I collagen synthesis; a decreased collagen synthesis similar to the in vivo situation is shown. The present study demonstrates the versatility of this FTSM in the validation of effectiveness and safety of GCs.

Photostability and efficacy studies of topical formulations containing UV-filters combination and vitamins A, C and E

It is already known that the photostability of a sunscreen is important for its performance on human skin. On the other hand, there are many formulations besides sunscreens containing combinations of UV-filters and daily use active substances with other claims like hydration and anti-aging effects. Vitamins A, C and E are frequently added in these kinds of products and it is not known if the UV-filters have some influence on the hydration and anti-aging effects of these vitamins on the skin as well as on their stability mainly when photounstable UV-filters like avobenzone and octyl methoxycinnamate are present in the formulation. Thus, the aim of this study was to evaluate the influence of two different UV-filters combinations, a photostable and a photounstable one, on the photostability as well as on the efficacy of a formulation containing vitamin A, C and E derivatives. The formulations that were investigated contained or not (vehicle: formulation 1) a combination of 0.6 % (w/w) vitamin A palmitate (1,700,000 UI/g), 2 % (w/w) vitamin E acetate and 2% (w/w) ascorbyl tetraisopalmitate (formulation 2) supplemented with a photounstable UV filter combination octyl methoxycinnamate (OMC), avobenzone (AVB) and 4-methylbenzilidene camphor (MBC) (formulation 3) or with a photostable UV filter combination OMC, benzophenone-3 (BP-3) and octocrylene (OC) (formulation 4). In the photostability studies, all formulations were spread onto a glass plate and exposed to UVA/UVB irradiation. The filter components and vitamins were quantified by HPLC analysis with detection at 325 and 235 nm and by spectrophotometry. To simulate the effects of these formulations daily use, all of them (formulations 1–4) were applied on the dorsum of hairless mice, which were submitted to a controlled light–dark cycle (and were not irradiated), once a day for 5 days. Transepidermal water loss (TEWL), water content of the stratum corneum and viscoelastic properties of the skin were analyzed by using different non-invasive Biophysics Techniques in order to evaluate hydration and anti-aging effects of these formulations as well as erythema to assess skin irritation. Histopathology, viable epidermal thickness as well as the number of epidermal cell layers were also evaluated. It was observed that both UV filters combinations (photounstable one containing OMC, AVB and MBC and photostable one containing OMC, BP-3 and OC) enhanced vitamin A photostability and F4 was more photostable than F3, in terms of vitamin A. In vivo efficacy studies showed that F2, F3 and F4 enhanced the viable epidermal thickness, the number of epidermal cell layers, TEWL and Uv/Ue parameter, when compared to the vehicle, which can suggest that they enhanced viable epidermis hydration and acted in cell renewal. However formulation 2 (containing only vitamins), which was the most photounstable formulation, provoked an irritation on hairless mouse skin, and consequently it cannot be considered as safe as the other formulations. It can be concluded that both UV filters combinations did not influence the hydration and anti-aging effects of the formulations containing the vitamins under study and reduced the skin irritation observed when the vitamins were present in the formulation. In addition, the photostable UV-filters combination had the highest recovery of vitamin A in the photostability studies. Finally, it could be suggested that the presence of UV-filters can be considered interesting for the reduction of skin irritation and the most suitable formulation was the one containing the combinations of vitamins A, C and E with photostable UV-filters.

Initial effects of UV-B radiation on stem surfaces of Stenocereus thurberi (organ pipe cacti)

Most studies on the botanical effects of UV-B radiation have been conducted over short time periods. Therefore, the consequences of long-term changes in levels of UV-B radiation to flora are poorly understood. Earlier studies with 14 species of tall, long-lived columnar cacti have shown that (1) all species are experiencing surface injuries that begin on equatorial-facing stem surfaces that eventually progress around stems; (2) cacti that are sun-shaded by surrounding vegetation show fewer surface injuries; and (3) these surface injuries are more prevalent now than in past times. The purpose of this study was to determine whether exposure to UV-B radiation under greenhouse exposures could induce stem surface injury symptoms similar to those of injured cacti. Daily exposures of 11 kJ m −2 of UV-B for 38 months produced a 40% decrease in the number of visible stomata of stems of Stenocereus thurberi (Engelman). This decrease in visible stomata was caused by a build-up of epicuticular waxes. Even when some stomata were visible on UV-B samples, epicuticular waxes occluded many stomata. Moreover, after 38 months of exposure to UV-B radiation, the number of epidermal cell layers increased from a normal of 1.7–1.9 to 2.3–2.6 layers. The increase in epidermal cell layers is important because scaling and barking of surfaces (surface injuries) of cacti in nature is caused by proliferation of epidermal cells. These results from controlled UV-B exposures are identical to initial microscopic events that occur to cacti under natural sunlight conditions that eventually lead to surface injuries and death of plants. These results show that UV-B radiation can alter the epidermal structure of S. thurberi and also suggest that UV-B radiation may be, at least in part, a causative agent of the surface injuries to long-lived columnar cacti in nature.

The epidermal barrier

A mature epidermis is an effective barrier which prevents dehydration from the loss of body water, poisoning from the absorption of noxious substances, and systemic infection from invading surface microorganisms. The epidermal barrier resides within the most superficial layer of the skin, the stratum corneum. In utero the fetus has no need for a skin barrier, so the stratum corneum does not start to develop until around 24 weeks' gestation. After 24 weeks there is a steady increase in the number of epidermal cell layers and in epidermal thickness, although it is not until around 34 weeks' gestation that a well-defined stratum corneum has completely developed. A weak epidermal barrier is, therefore, present is very preterm infants (<30 weeks' gestation) during the first 2–3 weeks of life and if the skin is damaged by trauma or disease.

Anti-tumor and anti-carcinogenic activities of triterpenoid, beta-boswellic acid.

Boswellin (BE), a methanol extract of the gum resin exudate of Boswellia serrata, contains naturally occurring triterpenoids, beta-boswellic acid and its structural related derivatives, has been used as a traditional medicine for the treatment of inflammatory and arthritic diseases. Topical application of BE to the backs of mice markedly inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced increases in skin inflammation, epidermal proliferation, the number of epidermal cell layers, and tumor promotion in 7,12-dimethylbenz[a]anthracene (DMBA)-initiated mice. Feeding 0.2% of BE in the diet to CF-1 mice for 10-24 weeks reduced the accumulation of parametrial fat pad weight under the abdomen, and inhibited azoxymethane (AOM)-induced formation of aberrant crypt foci (ACF) by 46%. Addition of pure beta-boswellic acid, 3-O-acetyl-beta-boswellic acid, 11-keto-beta-boswellic acid or 3-O-acetyl-11-keto-beta-boswellic acid to human leukemia HL-60 cell culture inhibited DNA synthesis in HL-60 cells in a dose-dependent manner with IC50 values ranging from 0.6 to 7.1 microM. These results indicate that beta-boswellic acid and its derivatives (the major constituents of Boswellin) have anti-carcinogenic, anti-tumor, and anti-hyperlipidemic activities.

The influence of Gyrodactylus salaris Malmberg 1957 (Monogenea) on the epidermis of Atlantic salmon, Salmo salar L., and brook trout, Salvelinus fontinalis (Mitchill): experimental studies.

The effect of Gyrodactylus salaris on the epidermal structure of hatchery-reared brook trout parr and Norwegian Atlantic salmon parr was evaluated. Both species were initially susceptible to this parasite, but whereas populations on salmon increased until the host died, brook trout responded to, and eventually eliminated, their infections. Salmon skin samples taken 14 days p.i. showed a reduced mucous cell concentration (less than 1500 cells mm-2 on the head compared with 2000 cells mm-2 in controls; the same trend was also seen in other sites) and the epidermis was thinner (48 μm compared with 60 μm on pectoral fins; similar trend seen in other sites) than in uninfected controls kept under identical conditions. Brook trout skin samples were taken 50 days p.i., when the hosts had responded to, and almost eliminated, their infections. No change was then observed in mucous cell density, while the number of epidermal cell layers and the epidermal thickness of brook trout had increased slightly following infection. These results are related to the nature of the host response, and the thinning of the epidermis and loss of mucous cells may in some way be related to the inability of Norwegian salmon parr to respond to the parasite.

Laser Doppler measurements of cutaneous blood flow in ageing mice and rats

Laser Doppler velocimetry (LDV) is a non-invasive technique that measures capillary blood perfusion parameters (blood flow, volume and velocity) and can be used non-invasively to evaluate the effects of ageing on cutaneous blood perfusion. Male Fischer-344 rats (R) of 1, 2, 3, 8, 12, 16, 20 and 24 months and C57BL/6N mice (M) 1, 2, 3, 9, 15, 19 and 22 months ( n=6/mo) were used. Animals were anesthetized with ketamine/xylazine and LDV-measured blood flow was made on the backs of all animals. Five readings for each parameter were recorded in order to obtain a mean value of the individual. Skin biopsies (4 mm) were removed after LDV for assessing epidermal and dermal thickness and number of epidermal cell layers. The number of viable epidermal layers in M remained constant while in R it decreased with age. Epidermal thickness in both M and R decreased from 2–3 months and then remained constant. Dermal thickness decreased from 3 to 22 months in M, and increased in R from 1 to 2 months and remained constant. Blood flow of M increased between 1 and 2 months, remained constant to 19 months, then increased at 22 months; flow in R was constant except at 2 months. Thus age differences in epidermal and dermal thickness, and blood flow of M and R occur and should be considered when evaluating cutaneous toxicity studies in different-aged animals. These changes may potentially alter dermal absorption and/or distribution of xenobiotics.

Induction, repair and accumulation of thymin dimers in the skin of UV-B-irradiated hairless mice

A monoclonal antibody specific for cyclobutane thymine dimers in DNA was used in immunofluorescence studies to detect these lesions in skin sections taken from hairless mice that had been irradiated with UV-B. The dimer-specific fluorescence in epidermal cell nuclei was quantified with fluorescence microscopy through computer-mediated image processing and analysis. After a UV-dose of 500 J/m2, thymine dimers could easily be detected. Rapid removal of these lesions in vivo was observed during the first 4 h after exposure, but at 24 h approximately 40% of the dimers still persisted. Thymine dimers accumulated in the skin of mice subjected chronically to a dose regimen of 1000 J/m2 UV-B per day. In the first week strong accumulation of dimers was observed. At day 3 to 4 it reached a maximum, after which a decrease to a more constant level occurred. Concomitant with this decrease the number of epidermal cell layers increased after the first week. After 3 months of irradiation, mice started to develop skin tumors. At that time point the epidermis had thickened to contain up to 10 cell layers, compared to 1-2 layers in unirradiated mice, but thymine dimers were still induced.

Stomata and Stomatal Clusters in Begonia: Ecological Response in Two Mexican Species

Many species in the genus Begonia have stomata that occur in clusters; clusters are an unusual character and have an extremely limited distribution among the higher plants. Six populations of Begonia heracleifolia Cham. et Schlecht. and nine populations of B. nelumbiifolia Cham. et Schlecht. were sampled from tropical forests in Mexico to determine the ecological response of the stomata and clusters of these species. Several characters, including mean cluster size, number of stomata/duster, length, and number of stomata/mm2, were analyzed to determine variation within and between populations; the latter three characters are responsive to elevation in B. nelumbiifolia, but only mean cluster size and number of stomata/ mm2 are responsive to elevation in B. heracleifolia. Ecological evidence from this study supports the hypothesis that clusters in Begonia assist in water conservation. A distributional analysis of sympatric populations of these species at a waterfall site in Chiapas indicates that the relative density of B. nelumbiifolia is greater near the pool formed by the falls, and that the relative density of B. heracleifolia is greater away from the pool. B. nelumbiifolia has a lower mean cluster size and a lower range of cluster sizes than B. heracleifolia. The hypothesis is further supported by differences in the range of cluster sizes between populations occupying different habitats and substrate types: populations growing on rocks near waterfalls have larger clusters than populations collected from soil substrates. THIS INVESTIGATION CONSIDERS THE ECOLOGICAL RESPONSE OF STOMATA in Begonia, a pantropical genus of the Begoniaceae induding approximately 1200 species (Barkley & Golding 1974). A cluster is a group of two or more guard cells belonging to one stomatal chamber, where the individual stomata within the duster group are separated from each other by subsidiary cells (Fellerer 1892). Epidermal cells are only observed between clusters, never within the duster group. Within the genus Begonia, some species are observed to have dusters, with much variation in the number of stomata per duster, but other species are observed to have stomata occurring only singly. Most vascular plants have stomata occurring singly; the occurrence of clusters is very limited within the higher plants. Some other taxa known to have clusters besides Begonia include Pagamea (Rubiaceae), and Saxifraga (Saxifragaceae) (Fellerer 1892), Gesneria, Heppiella, Halphophyllum, and Rytidophyllum (Gesneriaceae) (Metcalfe & Chalk 1950, Wiehler 1970, Skog 1976) and some species in the Bromeliaceae (T. Givnish, pers. comm.). Possibly the first report on clusters in Begonia was by Strasburger (1866-1867). The first to suggest that dusters function to reduce transpiration was Fellerer (1892), reporting that the distribution of dusters over the lower leaf surface provides larger spaces for water vapor to be trapped, though he provided no anatomical or physiological support for this suggestion. Evidence indicating a positive correlation between the number of epidermal cell layers and the number of stomata/duster has been presented by Boghdan and Barkley (1972), though no function has been advanced. A list of 122 species of Begonia and their corresponding cluster sizes has been reported by Neubauer (1967) and Neubauer and Bissler (1971). Of additional importance, Neubauer (1967) describes the presence of water-storing tissue in Begonia. Clearly important to the evolution of clusters in Begonia is the functional significance of their size, density, and the characteristics of their component stomata. In this paper, intraand interpopulation variation of these traits are described for two Mexican species, B. heracleifolia and B. nelumbiifolia, which occupy varying habitats and elevations throughout the tropical vegetation zones of Mexico. This paper provides ecological evidence supporting Fellerer's (1892) suggestion that dusters are a means of reducing transpiration.

Action de l’acide 13-cis-rétinoïque et du rétinoïde aromatique sur divers paramètres cutanés, chez le rat rendu hyperséborrhéique

Castrated rats submitted to androgenic stimulation present hyperseborrhea with an increase in foamy cells associated with an increase in cutaneous lipids and a change in the number of epidermal cell layers. 13-cis-retinoic acid and aromatic retinoid (Ro 10-9359) were given orally during 17 days (10 mg/kg) to castrated rats which had received a testosterone implant. Cyproterone acetate was chosen as the antiandrogenic drug; it was given at doses of 10 mg/kg i.m. once every other day. As opposed to cyproterone acetate, the two substances studied had no effect on the seminal vesicle and ventral prostate. 13-cis-retinoic acid and retinoic aromatic acid increased the total number of epidermal layers: In the case of 13-cis-retinoic acid, the increase involves especially the nonnucleated cell layers, whereas with retinoid aromatic acid it involves the nucleated cell layer. The number of sebaceous glands is not changed by either products, on the other hand, the number of foamy cells is considerably decreased and the weight of cutaneous lipids is decreased as well.