Reconstruction of stratum corneum in organotypically cultured canine keratinocyte-derived CPEK cells

The stratum corneum of epidermis is an essential barrier against the external environment and water loss. This study aimed to develop an organotypic culture model that targets the reconstruction of the stratum corneum using canine keratinocyte-derived CPEK cells. The CPEK cells cultured at the air-liquid interface became stratified and formed a stratum corneum-like layer on stratum spinosum- and stratum granulosum-like layers. The CPEK cells in the stratum granulosum-like layer expressed the cornified cell envelope (CCE)-related proteins loricrin and keratinocyte differentiation-associated protein. Organotypically cultured CPEK cells were considered to form a CCE at the stratum granulosum-like layer, allowing the formation of a stratum corneum-like layer. The organotypic culture of CPEK cells could be useful for studying the barrier function of canine stratum corneum.     

Structure of the epidermis in Ayrshire bullocks.

The living epidermis and stratum corneum of cattle, when measured on cryostat sections, were both found to be approximately 30 micrometer thick. However, the corneum contained about 30 cell layers, whereas the living epidermis was composed of only four. Histological processing involving fixation, dehydration and paraffin embedding, resulted in the loss of half of the stratum corneum and proved to be unsuitable for study of this layer. Lipid derived mainly from the sebaceous gland was present between the squames in the outer two thirds of the corneum probably in the form of an emulsion with sweat.     

Is the skin barrier abnormal in dogs with atopic dermatitis?

In mammalian skin, the stratum corneum exerts a barrier function that protects from transepidermal water loss and the penetration of exogenous molecules, such as allergens, from the environment. Recently, skin barrier defects have been shown to be of prime importance in the pathogenesis of human atopic dermatitis. In this review, we summarize the latest research data pertinent to the stratum corneum and barrier function of dogs with atopic dermatitis. At the time of this writing, there is increasing evidence that a skin barrier defect likely exists in dogs with atopic dermatitis. This barrier dysfunction is characterized by abnormal intercellular stratum corneum lipid lamellae, abnormal stratum corneum morphology, reduced and abnormal ceramide content and, in some but not all dogs, abnormal filaggrin expression. In association with these changes, there is higher transepidermal water loss in atopic than in normal canine skin. Furthermore, atopic inflammation appears to worsen transepidermal water loss and filaggrin expression. It remains unknown, however, if the changes observed are primary (i.e. of genetic origin) or secondary to atopic inflammation that also exists even in clinically normal skin. Finally, whether or not a therapeutic intervention aimed at restoring a dysfunctional skin barrier is of any clinical benefit to atopic dogs has not yet been proven unequivocally.     

Elektronenmikroskopisch-zytochemische Untersuchungen an Zellmembranen der Hornzellen vom Vormagenepithel der Ziege*

Ultrahistochemical studies on the plasma membrane of stratum corneum cells in the proventricular epithelium of the goat Using ultrahistochemical methods carbohydrate-rich substances and SH-groups could be localized on the plasma membrane of stratum corneum cells in the proventricular epithelium of the goat. SH-groups were present only on the inner lamella of the plasma membrane while mucosubstances were present on both sides. The functional significance of both these substances is still not understood, especially whether they take part in the specific transport mechanism present in the proventricular epithelium.     

Feeding of the chewing louse Damalinia ovis (Schrank) (Phthiraptera:Trichodectidae) on sheep

The possibility that Damalinia ovis ingests intact epidermis could explain economically important irritation behaviour by infested sheep. To test this, feeding lice were observed on sheep by hand lens and macrophotography and on light and scanning electron microscope preparations. Aspects of feeding behaviour were described, particularly an epidermal ingestion posture. Louse ingesta were examined in paraffin and frozen sections. Lipid-covered stratum corneum squames were identified in crop, midgut, rectum and faeces. Nucleated keratinocytes from inner epidermal strata were not seen, neither were wool fibres. Vertical frozen sheep skin sections, with feeding lice cryofixed by liquid nitrogen, showed mandibles engaged in the outer stratum corneum of the epidermis. The epidermal origin of some ingesta was confirmed by confirming lice over sheep whose skin was stained with Oil Red O, whose colour was seen in crop, midgut, rectum and faeces of harvested lice. Lipase was found in louse midgut. It was concluded that sebaceous secretions may form an important component of the D. ovis diet. The relative contribution from loose scurf or from stratum corneum squames was not determined. Mechanical stimuli by feeding lice did not seem to be the source of host irritation. The role of sensitising agents in louse brei filtrates was investigated with inconclusive results. Intradermal injections of louse faeces did not elicit a demonstrable response.     

Light and electron microscopic comparisons of cutaneous fibromas in white-tailed and mule deer

Cutaneous fibromas of white-tailed deer (Odocoileus virginianus), when compared with normal skin of the same species, had a thinner basement membrane; thickened stratum spinosum with numerous melanocytes, desmosomes, polyribosomes, and tonofilaments; focal hyperplasia of the stratum granulosum containing numerous large, electron-dense keratohyalin granules with irregular borders and containing occasional cells with diffuse intranuclear virus particles; and a moderately thickened stratum corneum with (although rarely) small crystalline arrays of virus particles. Normal mule deer (Odocoileus hemionus) skin was structurally similar to that of the white-tailed deer. Mule deer fibromas were similar to those in white-tailed deer, except for diffuse thickening of the stratum granulosum (the cells of which contained large keratohyalin granules of various electron densities with occasional composite granules) and except for a markedly thickened stratum corneum that contained numerous intranuclear viral inclusions. In negatively stained homogenates of tumors from both deer species, viral particles resembled papillomaviruses.     

Sarcoptic mange in free-ranging raccoon dogs (Nyctereutes procyonoides) in Japan

Sarcoptes scabiei infestation was diagnosed in three freshly dead free-ranging raccoon dogs (Nyctereutes procyonoides) in Kanagawa Prefecture, Japan. The dogs presented with an alopecic pruritic skin disease, with signs of alopecia on the ears, muzzle, around the eyes, elbow, thigh and the neck, and hyperpigmented and crusted skin lesions, which had a severe malodour. Skin scrapings revealed the presence of the mite Sarcoptes scabiei. Histopathology of lesions demonstrated marked acanthosis, hyperkeratosis, parakeratosis and fungal elements, which were subsequently identified as Acremonium sp., Alternaria sp. and an unknown fungus. Mite segments were located mainly in the stratum corneum and also in the stratum granulosum. Tunnels could be observed in the hyperkeratotic stratum corneum. Scanning electron microscopy (SEM) revealed the tortoise-like Sarcoptes scabiei with four long bristles, suckers and blade-like claws on legs 1 and 2, cuticular spines, prominent body striations and a terminal anus. SEM also revealed an adult female mite digging a tunnel with the head wedged into the very end of the closed burrow. Tunnels filled with eggshells, corneocyte debris and faecal pellets were also observed.     

盐胁迫下2种樱桃叶片解剖结构的变化

为了筛选耐盐樱桃砧木,用于天津市周边轻度盐碱地区栽培,本试验通过徒手切片的方法,研究了两种樱桃砧木在盐胁迫下的叶片解剖结构变化。结果表明：在盐胁迫下,四川樱桃的叶片增厚了3.99%,大青叶的减少了2.68%;大青叶的表皮层细胞增厚了23.6%,四川樱桃的减少了3.84%;大青叶的角质层增厚3.57%,四川樱桃的减少了18.31%;四川樱桃的栅栏组织层变化不大,大青叶的减少了16.42%;四川樱桃的海绵组织层增厚了31.96%,大青叶的增厚了21.27%;四川樱桃的栅栏组织和海绵组织层厚度的比值变小、减少了29.17%,大青叶的减少了20.80%。盐胁迫使大青叶叶片表皮细胞层变厚,角质层加厚,栅栏组织层变薄,海绵组织层加厚,整个叶片变薄。盐胁迫使四川樱桃表皮细胞层变薄,角质层变薄,海绵组织层加厚,整个叶片变厚。从盐胁迫下的2种樱桃叶片结构的变化综合分析认为大青叶的耐盐性明显高于四川樱桃。     

Investigation into the dosage of dietary sphingomyelin concentrate in relation to the improvement of epidermal function in hairless mice

We previously found that dietary sphingomyelin (SPM) concentrate from bovine milk improved epidermal function. In this study, we investigated the dosage of dietary SPM concentrate from bovine milk in relation to the improvement of epidermal function. Thirteen-week-old hairless male mice were separated into four experimental groups, each fed one of four types of experimental diet: the control group, the low SPM group, the medium SPM group and the high SPM group. The mice were each fed the experimental diet for 6 weeks. The stratum corneum hydration and the transepidermal water loss (TEWL) were measured using a Corneometer and a Tewameter at 3 weeks and 6 weeks. After the feeding period, ceramides in the stratum corneum were analyzed. We found that the stratum corneum hydration in all the SPM groups was significantly higher than that in the control group, whereas TEWL in all the SPM groups was significantly lower than that in the control group. Ceramides increased significantly in mice fed the medium SPM diet and statistically tended to increase in mice fed the high SPM diet. Our results indicate that a daily intake of 17 mg SPM concentrate is enough to improve epidermal function in hairless mice.     

Experimental bovine Trichophyton verrucosum infection. Comparison of the rate of epidermal cell proliferation and keratinisation in non-infected and reinoculated cattle.

The rate of epidermal cell renewal in normal bovine skin and that reinoculated with Trichophyton verrucosum was measured using a radioautographic technique. The transit times of both nucleated and fully keratinised cells were measured in sequential biopsy samples removed at predetermined periods after intradermal inoculation with radio-labelled isotopes. The total time taken for cells of the basal layer to travel to the point of desquamation in the stratum corneum was 18 days in normal cattle. In similar areas on cattle that had been reinoculated with T verrucosum the total epidermal cell renewal time was reduced to 12 days. Increased protein synthesis, as measured by incorporation of radio-labelled nucleoside was evident in basal cells within 24 h of reinoculation with the fungus. The nucleated epidermal cell thickness had almost doubled in areas of reinoculated skin within 72 h and increased cell proliferation was maintained for at least 10 days. Desquamation of the thickened stratum corneum had occurred within seven days of reinoculation with the fungus.     

Some observations on sheep sarcoptic mange in Tehran province,Iran

Sarcoptes scabiei infestation was diagnosed in 278 sheep from 12 fatling flocks. The sheep presented crusted skin lesions initially appear on the lips or nostrils, the lesion on nostrils also extend towards around the eyes, the supraorbital fossae and in some cases over entire face. The infested male lambs by mating behavior in fatling flocks caused transmitting the infection to fat tail area and scrutum. Histopathological study of lesions demonstrated marked acanthosis, hyperkeratosis, parakeratosis. Tunnels could be observed in the hyperkeratotic stratum corneum and mite segments were located mainly in the stratum corneum and also in the stratum granulosum. Attempts to eliminate S. scabiei var. ovis were made in 3 naturally infested sheep herds, by two dippings with two weeks interval with Amitraz, Cypermetrin and Prompetamphos. The results of this study indicate that acaricidal treatment of S. scabiei var. ovis in 3 naturally infested herds was successful, but a few cases of reinfestation were found in each treated group.     

Histological and functional comparisons of four anatomical regions of porcine skin with human abdominal skin

Because of the shortage of human skin for research purposes, porcine skin has been used as a model of human skin. The aim of this study was to identify the region of German Landrace pig skin that could be used as the best possible substitute for human abdominal skin. Porcine samples were collected from the ear, flank, back and caudal abdomen; human abdominal skin samples were excised during plastic surgery. Histological and ultrastructural assessments were carried out on the epidermis and dermis, with emphasis on the dermo‐epidermal interface length, dermo‐epidermal thickness ratio as well as densities of; hair follicles, arrector pili muscles, blood vessels and sweat glands. In the pig, the barrier function of the four anatomical regions was assessed. Results showed that both histologically and ultrastructurally, all four regions of porcine skin were similar to human skin. These include the shapes of keratinocytes, structure of cell contacts and presence of Weibel Palade bodies in endothelial cells. Other parameters such as the thickness of epidermis, the thickness of stratum basale, spinosum and granulosum and the number of cell layers in the stratum corneum were similar in human abdominal and in all four regions of porcine skin. However, there were also significant differences especially in the thickness of the stratum corneum, the dermo‐epidermal interface length and the blood vessel density.     

Electron microscopic observations of stratum corneum intercellular lipids in normal and atopic dogs.

The barrier function of mammalian skin is maintained by intercellular stratum corneum lipids. In human patients with atopic dermatitis, an abnormal lipid barrier results in dry skin and increased transepidermal water loss. At this time, it is not known if a defective lipid barrier is present in atopic dogs. Normal and atopic canine skin were postfixed in ruthenium tetroxide and studied using transmission electron microscopy to determine structural differences within stratum corneum lipids. Intercellular lipid lamellae were graded on a semiquantitative scale. The deposition of stratum corneum lipid lamellae in atopic canine skin appeared markedly heterogeneous compared with that seen in normal canine skin. When present, the lamellae often exhibited an abnormal structure. The continuity and thickness of the intercellular lipid lamellae were significantly less in nonlesional atopic than in normal canine skin. These preliminary observations suggest that the epidermal lipid barrier is defective in atopic canine skin. Additional studies are needed to further characterize the biochemical defect and to possibly correct it with nutritional and/or pharmacologic intervention.     

离体瘤胃上皮细胞在瘤胃代谢中的研究进展

反刍动物瘤胃上皮由基底层、棘层、粒层和角质层等四层组成,在瘤胃发酵终产物的代谢中具有重要作用,但其形态学受动物本身及饲喂制度等诸多因素的影响,造成细胞代谢活性上的差异。现在,应用离体瘤胃上皮细胞,使研究其组织形态学和代谢成为可能。     

饲粮中不同比例桑叶粉对湖羊瘤胃上皮组织结构的影响

本试验旨在研究饲粮中不同比例的桑叶粉对育肥湖羊瘤胃上皮组织结构的影响。选取3月龄育肥湖羊40只,随机分为5组,每组8只。各组用桑叶粉分别替代饲粮中精料的0(A组)、15%(B组)、30%(C组)、45%(D组)、60%(E组)。预试期2周,正试期8周。结果表明:1)B组和C组瘤胃重/复胃重显著高于A组(P0.05)。2)各组瘤胃乳头宽度的差异不显著(P0.05)。3)对于瘤胃上皮的角质层宽度,A组高于其他各组,其中显著高于C组和D组(P0.05);对于瘤胃上皮颗粒层宽度,除D组显著高于E组(P0.05)外,其余各组间差异不显著(P0.05);对于棘突层和基底层宽度,与A组相比,桑叶粉处理能提高棘突层和基底层的宽度,但是作用不显著(P0.05),D组和B组的基底层宽度显著高于C组(P0.05)。总之,用桑叶粉替代15%~45%的精料能在一定程度上提高湖羊复胃的重量,促进的棘突层和基底层细胞的分裂,从而促进瘤胃上皮组织发育,同时,也有效降低了瘤胃上皮角质层的宽度。     

The Structure and Function of Epidermal Lipids

Abstract— This review article examines current knowledge of the structure and function of epidermal lipids in human and veterinary dermatology. Dynamic transformations in lipid composition and structure occur as cells migrate through the epidermis. The lipids which are formed have a direct effect on epidermal functions. Ceramides appear to be the most important lipid component for lamellar arrangement in the stratum corneum and barrier protection. Polyunsaturated fatty acids in the epidermis are also important because they are incorporated into the ceramides. Additionally, arachidonic acid is bound to the phospholipid portion of cell membranes and is the most important precursor of endogenous eicosanoids. The eicosanoids are vital for epidermal homeostasis and play an important role in the pathogenesis of inflammatory dermatoses when produced in abnormal quantities. In addition to barrier protection, other vital epidermal functions associated with the lipids include stratum corneum water-holding, cohesion and desquamation of corneocytes, and control of epidermal proliferation and differentiation.     

Histochemical localization of adenosine triphosphatase activity in bovine ruminal epithelium.

A fine-structural histochemical technique was used to localize magnesium-dependent adenosine triphosphatase (Mg-ATPase) activity in ruminal mucosa. Precipitate appeared on the cytoplasmic surface of the plasmalemma in cells of the upper stratum spinosum, the stratum granulosum, and the deepest layer of the stratum corneum. This ATPase activity was sensitive to glutaraldehyde fixation and possibly to ouabain, but was unaffected by sodium and potassium. The preponderance of Mg-ATPase activity in bovine ruminal epithelium may make it impossible to detect sodium-potassium-activated adenosine triphosphatase ((Na + K)-ATPase) activity histochemically. A Mg-ATPase activity also occurred in mitochondria of the stratum spinosum and stratum granulosum. None of the ruminal sections hydrolyzed adenosine diphosphate, inosine triphosphate, or beta-glycerophosphate when these compounds were used as substitute substrates for adenosine triphosphate. When adenosine-5'-monophosphate was the available substrate, a reaction product appeared in the same layers as Mg-ATPase activity, but the reaction product was confined to the intercellular space.     

The epidermal location and possible feeding site of Psorergates ovis, the sheep itch mite

Skin biopsies from two Merino sheep heavily infested with Psorergates ovis were immersed in liquid nitrogen and cut into vertical frozen sections stained with lipophilic Sudan IV or Oil Red O and haematoxylin. A survey of the lateral distribution of mite sections showed a majority (ca 80%) were in or within 0.2 mm of the follicle mouth. A survey of vertical distribution showed no mite penetration deeper than inner stratum corneum where 57% of mite sections were seen; 30% were within outer stratum corneum or scurf; 13% were on the outer surface and less than 1% were detached. Lipid was the only material seen within stained mites at a location considered to be gut. This was supported by dosing sheep with quinacrine, taking biopsies at Day 6 and Day 14 and examining frozen sections under blue light. Fluorescent lipid was seen at a location considered to be mite gut. From these results it was recommended that acaricide treatments against P. ovis be lipophilic and administered transepidermally because less than 15% of mites were at a superficial location likely to be reached by topical application.     

Ichthyosis and hereditary cornification disorders in dogs

The stratum corneum (SC), the outermost layer of the epidermis, serves a crucial role in maintaining body hydration and protection from environmental insults. When the stratum corneum is injured or when the genetic blueprints are flawed, the body is at risk of dehydration, secondary infections and allergen sensitization. Advancements in veterinary dermatology have revealed a wide gamut of disease from relatively benign to lethal that specifically arise from flawed structural proteins, enzymes or lipids needed to create the corneocytes and lipid bilayers of the SC. Some conditions closely mimic their human counterparts while others are unique to the dog. This review will focus on forms of ichthyosis in the dog.     

Macro-microscopic study on the toepad of ostrich (Struthio camelus)

The ostrich foot has four toepads, two on the 3rd digit, one on the 4th digit and one at metatarso-phalangeal joint. Previous studies have not detailed the histo-morphological structure of these toepads. In this study, we have described the macroscopic and microscopic structures of the toepad of ostrich (Struthio camelus). Numerous papillae with different direction, length and thickness have been observed grossly on the ventral surface of each toepad. Histological examinations have revealed that the epidermis of the ostrich toepad, similar to other digitigrades, consists of an outer stratum corneum and an inner stratum germinativum (which is subdivided into basal, intermediate and transitional layers). The stratum corneum has several layers of flattened horny cells. The nuclei of basal cells have several mitotic figures. The cytoplasm of the stratum germinativum cells has multiple lipid droplets and multigranular bodies (in transitional cells only). Scanning electron microscopic examination revealed presence of collagen fibers in mid and deep dermis of each toepad. These fibers run parallel and connect to each other by very thin fibrils which are branched, crossed with each other in an oblique direction. Such arrangement of these collagen fibers, thin fibrils and presence of digital cushion are likely to be responsible for the protection of the underlying soft tissues and absorption of concussion.