Morphometric and histopathological evaluation of modified Elnady's plastinated tissue compared to non-plastinated tissue: Highlighting its relevance for teaching and research.

The present study aims to evaluate the morphometric and histopathological properties of Modified Elnady's plastinated tissue after a period compared to non-plastinated tissue. The plastination technique is utilized in research and teaching due to the potential health risks associated with prolonged exposure to formalin. The tissues and organs are permanently dried during plastination and can be used for further anatomical, histopathological and surgical educational purposes. This method involves drying tissue and allowing synthetic materials like glycerin to permeate it. The study compared non-plastinated and plastinated tissue post-plastination to determine if structural alterations differed from those linked to plastination. The study examined the histopathological examination of dogs' skin, muscles, liver, lung, and intestine using formalin-fixed organs for paraffin embedding and previously plastinated organs for a plastinated group. The study examined non-plastinated and plastinated tissues, their histological composition and biometric parameters revealing typical structures in the non-plastinated group. Plasmodiumted tissues exhibited a compacted appearance, volume changes, nuclear clarity, and cytoplasmic hypereosinophilia, with statistical differences between the two groups. The study reveals that plastinated tissues, after 5 years of plastination, maintain their histological architecture well, with some exceptions. Plastinated tissues can be utilized in future microscopic and immunological studies and will be beneficial for teaching and research.

A diadectid skin impression and its implications for the evolutionary origin of epidermal scales.

Corneous skin appendages are not only common and diverse in crown-group amniotes but also present in some modern amphibians. This raises the still unresolved question of whether the ability to form corneous skin appendages is an apomorphy of a common ancestor of amphibians and amniotes or evolved independently in both groups. So far, there is no palaeontological contribution to the issue owing to the lack of keratin soft tissue preservation in Palaeozoic anamniotes. New data are provided by a recently discovered ichnofossil specimen from the early Permian of Poland that shows monospecific tetrapod footprints associated with a partial scaly body impression. The traces can be unambiguously attributed to diadectids and are interpreted as the globally first evidence of horned scales in tetrapods close to the origin of amniotes. Taking hitherto little-noticed scaly skin impressions of lepospondyl stem amniotes from the early Permian of Germany into account, the possibility has to be considered that the evolutionary origin of epidermal scales deeply roots among anamniotes.

Cellular structure of dinosaur scales reveals retention of reptile-type skin during the evolutionary transition to feathers.

Fossil feathers have transformed our understanding of integumentary evolution in vertebrates. The evolution of feathers is associated with novel skin ultrastructures, but the fossil record of these changes is poor and thus the critical transition from scaled to feathered skin is poorly understood. Here we shed light on this issue using preserved skin in the non-avian feathered dinosaur Psittacosaurus. Skin in the non-feathered, scaled torso is three-dimensionally replicated in silica and preserves epidermal layers, corneocytes and melanosomes. The morphology of the preserved stratum corneum is consistent with an original composition rich in corneous beta proteins, rather than (alpha-) keratins as in the feathered skin of birds. The stratum corneum is relatively thin in the ventral torso compared to extant quadrupedal reptiles, reflecting a reduced demand for mechanical protection in an elevated bipedal stance. The distribution of the melanosomes in the fossil skin is consistent with melanin-based colouration in extant crocodilians. Collectively, the fossil evidence supports partitioning of skin development in Psittacosaurus: a reptile-type condition in non-feathered regions and an avian-like condition in feathered regions. Retention of reptile-type skin in non-feathered regions would have ensured essential skin functions during the early, experimental stages of feather evolution.

Hydradermabrasion through the lens of Line-Field Confocal Optical Coherence Tomography.

BACKGROUND: Hydradermabrasion, also known as "HydraFacial," is an exfoliative cosmetic procedure for skin rejuvenation that has gained popularity. Despite its increasing popularity, clinical studies validating its efficacy with non-invasive assessment of histological changes to the skin, are scarce. In this study, we used Line-Field Confocal Optical Coherence Tomography (LC-OCT), an optical imaging device, to non-invasively visualize microscopic changes to skin anatomy after hydradermabrasion treatment. MATERIALS/METHODS: Eight volunteers (Fitzpatrick skin types II-V) were recruited for this study. Images, using LC-OCT (DeepLive, DAMAE medical) were obtained before and after hydradermabrasion and at 2 weeks post-treatment. A commercially available hydradermabrasion device was utilized to perform the dermabrasion. RESULTS: In the epidermis, initially, a decrease in the average thickness of the stratum corneum, from 9.42 to 6.67 µm was visualized in LC-OCT images after hydradermabrasion. However, at 2 weeks of follow-up, the average stratum corneum thickness was 9.75 µm, resulting in an overall increase in the average thickness after treatment. Improved homogenization of the stratum corneum and decreased number of undulations in the epidermis post-treatment were also visualized. In all the subjects, the superficial dermis appeared stretched, which returned to baseline by the 2-week follow-up. At the 2-week follow-up, there were no visible differences in the quality and quantity of collagen fibers in the dermis. CONCLUSION: In our study, LC-OCT images of the epidermis and dermis demonstrated microscopic features of skin rejuvenation when treated with hydradermabrasion. Thus, not only highlighting the efficacy of hydradermabrasion but also the potential of LC-OCT to serve as a tool for visualizing the microscopic effects of cosmetic procedures on skin anatomy.

More potential uses of specific perforator flaps in the calf - A cadaveric study on the subdermal vascular structure of the lower leg.

BACKGROUND: The perforator flap has garnered significant interest since its inception due to its advantage of not needing a vascular network at the deep fascial level. Perforator flaps are commonly utilized in different flap transplant surgeries, and the thigh flap is presently the most widely used perforator flap. Is it possible for the calf to replace the thigh as a more suitable site for harvesting materials? Currently, there is a lack of relevant anatomical research. This study aims to address this question from an anatomical and imaging perspective. METHODS: This study used cadavers to observe the branches and courses of perforators on the calf and the distribution of skin branches using microdissection techniques, digital X-ray photography, and micro-computed tomography techniques. RESULTS: The perforators had three main branches: the vertical cutaneous branch, the oblique cutaneous branch, and the superficial fascial branch. The superficial fascial branch traveled in the superficial fascia and connected with the nearby perforators. The vertical and oblique cutaneous branches entered the subdermal layer and connected with each other to create the subdermal vascular network. CONCLUSIONS: We observed an intact calf cutaneous branch chain between the cutaneous nerve and the perforator of the infrapopliteal main artery at the superficial vein site. Utilizing this anatomical structure, the calfskin branch has the potential to serve as a substitute for thigh skin flap transplantation and may be applied to perforator flap transplantation in more locations.

Cellular patterning and cyto-architectural organization of the skin of electric catfish (Malapterurus electricus, Siluriformes) with a particular emphasis on its ampullary electroreceptor.

The functional morphology of the skin of Malapteruridae is presumably evolved to cope with a diversified range of ambient physiological, environmental, and behavioral conditions. Herein, we firstly characterized the microstructures and intriguing patterning of the skin of twelve adult electric catfish (Malapterurus electricus, Malapteruridae) using histological, histochemical, immunofluorescent, and ELISA standard methodology. The skin comprises three sequentially-oriented layers: the epidermis, dermis, and hypodermis with a significantly increased thickness of the former. The epidermis contains four types of cells: the surface epithelial cells, mucous cells, granular cells, and club cells. We defined distinctive ampullary electroreceptors in the outer epidermis that possess flask-shaped sensory crypt containing electroreceptor cells together with vertical collagen rods. Dermis and hypodermis are composed of connective tissue; however, the former is much more coarse and dense with comparable reactivity for Masson-Goldner trichrome (MT). Placing our data in the context of the limited body of previous work, we showed subtle changes in the expression of mucin subunits together with cytoskeletal fractions of collagens, myosin, F-actin, keratins, and tubulins. Taken as a whole, our results convincingly showed that the skin of M. electricus shares some structural similarities to other Siluriformes, however, it has some functional modifications that are implicated in protection, defense, and foraging behavior.

Histological changes of the skin during postembryonic development of the crested newt Triturus ivanbureschi (Urodela, Salamandridae).

BACKGROUND: Amphibian skin has been studied for many decades, especially the metamorphic changes in the skin of frogs. Less attention has been paid to salamander skin. Here, we describe changes in the skin structure during postembryonic development in a salamandrid species, the Balkan crested newt Triturus ivanbureschi. METHOD: Using traditional histological techniques we examined the skin in the trunk region of three premetamorphic larval stages (hatchling, mid larval and late larval) and two postmetamorphic stages (juvenile, just after metamorphosis, and adult). RESULTS: In larval stages, skin consists only of the epidermis, which gradually develops from the single epithelial cell layer in hatchlings, to a stratified epidermis with gland nests and characteristic Leydig cells at the late larval stage. During metamorphosis, Leydig cells disappear, and the dermal layer develops. In postmetamorphic stages, skin is differentiated on stratified epidermis and the dermis with well-developed glands. Three types of glands were observed in the skin of the postmetamorphic stages: mucous, granular and mixed. Gland composition appears to be stage- and sex-specific, with juveniles and adult female being more similar to each other. In juveniles and adult female, there are a similar proportion of glands in both dorsal and ventral skin, whereas in adult male granular glands dominated the dorsal skin, while mixed glands dominated the ventral skin. CONCLUSION: Our results provide a baseline for future comparative research of skin anatomy in salamanders.

Morphology of coat and skin of small ruminants reared in the Brazilian semi-arid region.

The structure of the coat and integument of small ruminants reared in semi-arid regions have valuable characteristics that favor their adaptation to the region. The objective of this study was to evaluate the structural characteristics of the coat and integument and sweating capacity of goats and sheep in the Brazilian semi-arid region, using 20 animals, 10 of each breed, 5 males and 5 females of each species, grouped in a completely randomized design in a 2 x 2 factorial scheme (2 species and 2 genders) with 5 replicates. The animals were already being kept under the influence of high temperatures and levels of direct solar radiation before the day of the collections. At the time of the evaluations, ambient temperature was high, with low relative humidity. The pattern of epidermal thickness and sweat glands per body region was superior in sheep (P < 0.05), and the number of hair follicles and sweat rate were similar (P > 0.05) between the species. There was no difference (P > 0.05) in the evaluated characteristics between the genders, showing that they are not influenced by hormones. The morphology of the coat and skin of these animals showed a superiority of goats compared to sheep.

Morphological pattern of the dermal denticles of the Southern sawtail catshark Galeus mincaronei Soto, 2001.

Dermal denticles cover the skin of sharks for protection and may have additional functions, depending on the environment. The aim of the present study was to analyze the morphological pattern of dermal denticles across the body of the poorly known deep-water catshark Galeus mincaronei, which is endemic to Southern Brazil. Additionally, we aimed to identify differences between sexes and stages of sexual maturity. For this purpose, we analyzed patches of eight skin samples from body regions, that is, the head, body, and tail. Dermal denticles were imaged using scanning electron microscopy. Measurements of crown morphological variations (length and width) and density of dermal denticles were performed. Nine characters of dermal denticle morphology were selected to describe a morphological pattern using principal component analysis (PCA). The first PCA axis explained 45.2% of the variation, the second explained 33%, and the third explained 14.3%, together explaining 92.5% of the total variation in denticle morphology. We identified three groups of dermal denticle crown morphologies and their possible functions. The first was composed of nostril and snout denticles, which might suggest abrasion strength functions; the second was composed of most body denticles, such as those in the cranium, on the left side of the body, and on the pectoral, dorsal, and caudal fins, which might be related to generalized functions; and the third was composed of only caudal crest denticles, which might indicate defense functions with hydrodynamic properties in G. mincaronei. Likewise, our results reveal variations in dermal denticle morphology and arrangement along the three maturity stages considered in both sexes. Similarly, sexual dimorphism in the crown width and morphology of dermal denticles was observed in developing and mature individuals. Our results are the first to reveal the morphological variation of dermal denticles in relation to function, sex, and ontogeny of individual G. mincaronei.

Unravelling the structural variation of lizard osteoderms.

Vertebrate skin is a remarkable organ that supports and protects the body. It consists of two layers, the epidermis and the underlying dermis. In some tetrapods, the dermis includes mineralised organs known as osteoderms (OD). Lizards, with over 7,000 species, show the greatest diversity in OD morphology and distribution, yet we barely understand what drives this diversity. This multiscale analysis of five species of lizards, whose lineages diverged ∼100-150 million years ago, compared the micro- and macrostructure, material properties, and bending rigidity of their ODs, and examined the underlying bones of the skull roof and jaw (including teeth when possible). Unsurprisingly, OD shape, taken alone, impacts bending rigidity, with the ODs of Corucia zebrata being most flexible and those of Timon lepidus being most rigid. Macroscopic variation is also reflected in microstructural diversity, with differences in tissue composition and arrangement. However, the properties of the core bony tissues, in both ODs and cranial bones, were found to be similar across taxa, although the hard, capping tissue on the ODs of Heloderma and Pseudopus had material properties similar to those of tooth enamel. The results offer evidence on the functional adaptations of cranial ODs, but questions remain regarding the factors driving their diversity. STATEMENT OF SIGNIFICANCE: Understanding nature has always been a significant source of inspiration for various areas of the physical and biological sciences. Here we unravelled a novel biomineralization, i.e. calcified tissue, OD, forming within the skin of lizards which show significant diversity across the group. A range of techniques were used to provide an insight into these exceptionally diverse natural structures, in an integrated, whole system fashion. Our results offer some suggestions into the functional and biomechanical adaptations of OD and their hierarchical structure. This knowledge can provide a potential source of inspiration for biomimetic and bioinspired designs, applicable to the manufacturing of light-weight, damage-tolerant and multifunctional materials for areas such as tissue engineering.

The use of optical coherence tomography for skin evaluation in healthy rats.

BACKGROUND: Noninvasive diagnostic techniques allow for morphological and morphometric in vivo evaluation of the skin. Optical coherence tomography (OCT) is a method that allows visualization of dermal structures up to several 100 µm with a resolution of 3-7.5 µm. OBJECTIVES: The aim of the study was the morphological and morphometric assessment of rats' skin using SD-OCT. ANIMALS: Fifteen male Wistar rats, aged 3 and 8 months, weighing 350-450 g. MATERIALS AND METHODS: The skin of the plantar metatarsal area of the right pelvic limb was assessed. The measurements were performed using Spectral Domain Optical Coherence Tomography (SD-OCT) scans and histological images. RESULTS: Spectral Domain Optical Coherence Tomography could determine the boundary between the epidermis and the dermis. Apart from the stratum corneum (SC), it did not allow for the differentiation of the individual epidermal layers. In the SD-OCT and in the histological examination, the mean thicknesses of the layers (µm ± SD) were (respectively): SC 33.053 ± µm(SD 5.85, 29.675 ± 5.54; epidermis 88.2 ± 7.97, 65.126 ± 13.23; dermis 259.86 ± 18.29, 166.05 ± 31.88 µm. There was a correlation between the total epidermal SD-OCT and histological measurements (r = 0.43, p = 0.05). Bland-Altman plots revealed a bias of -19.18 (95% confidence interval) -39.21 to 0.84 µm) in the case of live epidermis (stratum granulosum, stratum spinous, stratum basale). CONCLUSIONS AND CLINICAL RELEVANCE: Spectral Domain Optical Coherence Tomography can be used to evaluate rat epidermis and dermis. The method enables the differentiation of the SC, as well as the epidermis and the dermis. SD-OCT and histological thickness dimensions of the epidermis and skin differ.

Contexte - Les techniques de diagnostic non invasives permettent une évaluation morphologique et morphométrique in vivo de la peau. La tomographie par cohérence optique (OCT) est une méthode qui permet de visualiser les structures dermiques jusqu'à plusieurs centaines de micromètres avec une résolution de 3 à 7,5 µm. Objectifs - Le but de l'étude était l'évaluation morphologique et morphométrique de la peau des rats par SD-OCT. Animaux - Quinze rats Wistar mâles, âgés de 3 et 8 mois, pesant 350-450 g. Matériels et méthodes - La peau de la zone métatarsienne plantaire du membre pelvien droit a été évaluée. Les mesures ont été réalisées à l'aide de scaners SD-OCT (Spectral Domain Optical Coherence Tomography) et d'images histologiques Résultats - Le SD-OCT a pu déterminer la frontière entre l'épiderme et le derme. En dehors de la couche cornée (SC), il n'a pas permis la différenciation des couches épidermiques individuelles. Au SD-OCT et à l'examen histologique, les épaisseurs moyennes des couches (µm ± SD) étaient (respectivement) : SC 33,053 ± µm (SD 5,85, 29,675 ± 5,54 ; épiderme 88,2 ± 7,97, 65,126 ± 13,23 ; derme 259,86 ± 18,29, 166,05 ± 31,88 µm). Il y avait une corrélation entre le SD-OCT épidermique total et les mesures histologiques (r = 0,43, P = 0,05) Les tracés de Bland-Altman ont révélé un biais de -19,18 (intervalle de confiance à 95 %) -39,21 à 0,84 µm) dans le cas d'épiderme vivant (stratum granulosum, stratum spinous, stratum basale). Conclusions et pertinence clinique - Le SD-OCT peut être utilisé pour évaluer l'épiderme et le derme de rat. La méthode permet de différencier le SC, ainsi que l'épiderme et le derme. Le SD-OCT et les dimensions d'épaisseur histologiques de l'épiderme et de la peau diffèrent.

Introducción - las técnicas de diagnóstico no invasivas permiten la evaluación morfológica y morfométrica in vivo de la piel. La tomografía de coherencia óptica (OCT) es un método que permite la visualización de estructuras dérmicas de hasta varios cientos de micrómetros con una resolución de 3 a 7,5 µm. Objetivos - El objetivo del estudio fue la evaluación morfológica y morfométrica de la piel de ratas mediante SD-OCT. Animales - Quince ratas Wistar macho, de 3 y 8 meses de edad, con un peso de 350 a 450 g. Materiales y métodos - Se evaluó la piel de la zona metatarsiana plantar del miembro pélvico derecho. Las mediciones se realizaron utilizando escaneos SD-OCT (Tomografía de Coherencia Óptica de Dominio Espectral) e imágenes histológicas. Resultados - SD-OCT pudo determinar el límite entre la epidermis y la dermis. Aparte del estrato córneo (SC), no permitía la diferenciación de las capas epidérmicas individuales. En la SD-OCT y en el examen histológico, los espesores medios de las capas (µm ± SD) fueron (respectivamente): SC 33.053 ± µm (SD 5.85, 29.675 ± 5.54; epidermis 88.2 ± 7.97, 65.126 ± 13.23; dermis 259.86 ± 18,29, 166,05 ± 31,88 µm. Hubo una correlación entre el SD-OCT epidérmico total y las mediciones histológicas (r = 0,43, P = 0,05). Las gráficas de Bland-Altman revelaron un sesgo de -19,18 (intervalo de confianza del 95 %) -39,21 a 0,84 µm) en el caso de epidermis viva (estrato granuloso, estrato espinoso, estrato basal). Conclusiones y relevancia clínica- SD-OCT se puede utilizar para evaluar la epidermis y la dermis de rata. El método permite diferenciar el SC, así como la epidermis y la dermis. Las dimensiones de grosor de la epidermis y la piel difieren entre SD-OCT y la histología.

Contexto - Técnicas diagnósticas não invasivas permitem a avaliação morfológica e morfométrica in vivo da pele. A tomografia de coerência óptica (OCT) é um método que possibilita a visualização de estruturas dérmicas de até centenas de micrômetros com uma resolução de 3-7,5 µm. Objetivos - O objetivo do estudo foi a avaliação morfométrica e morfológica da pele de ratos utilizando SD-OCT. Animais - Quinze ratos Wistar machos, de três a oito meses de idade, pesando de 350 a 450 g. Materiais e métodos - A pele da região metatársica plantar do membro pélvico direito foi avaliada. As mensurações foram realizadas utilizando o SD-OCT (Spectral Domain Optical Coherence Tomography) e imagens histológicas. Resultados - A SD-OCT foi capaz de determinar o limite entre derme e epiderme. A exceção do estrato córneo (SC), não foi possível a diferenciação das camadas da epiderme individualmente. Na SD-OCT e na avaliação histológica, as espessuras médias das camadas fora, (µm ± DP), respectivamente: SC 33,053 ± 5,85; 29,675 ± 5,54; epiderme 88,2 ± 7,97; 65,126 ± 13,23; derme 259,86 ± 18,29; 166,05 ± 31,88 µm. Houve correlação entre SD-OCT e avaliação histológica nas mensurações da epiderme total (r = 0,43, P = 0,05). Os gráficos de Bland-Altman revelaram um viés de -19,8% (95% de intervalo de confiança) - 39,21 a 0,84 µm) no caso da epiderme viva (estrato espinhoso, estrato granuloso e estrato basal). Conclusões e relevância clínica - SD-OCT pode ser utilizada para avaliar a derme e a epiderme de ratos. Este método permite a diferenciação do SC, bem como da derme e epiderme. Pode haver discrepância na espessura da epiderme e da pele na SD-OCT e análise histológica.

Comparative morphology of the paw pad of the main arboreal Xenarthras from Amazon.

Paw pads are specializations of the integument and important shock absorbers of the locomotor system, as well as pressure, pain, temperature, storage and excretion sensors. Aiming to describe the paw pad morphology of the main arboreal xenarthras species in the Amazon, 16 animals were studied, Bradypus variegatus (6), Choloepus didactylus (5), Tamandua tetradactyla (3) and Cyclopes didactylus (2) that after death were donated to the Animal Morphological Research Laboratory (LaPMA / Ufra). The corpses were thawed and fixed with 10% aqueous formalin solution. The paw pads were measured, photographed and removed by skin incision dorsally to them. Fragments were used for routine histological processing, using two staining techniques: Hematoxylin-Eosin (HE) and Gomori's Trichrome, in sections of 6 to 8 µm. Choloepus didactylus, Tamandua tetradactyla and Cyclopes didactylus have digital paw pads, one in each digit, and one palm, as well as a plantar, whose shapes and colours are distinct from each other. Bradypus variegatus, however, has only one palmar and one plantar pad. Histologically, they have keratinized stratified squamous epithelium, supported by a large amount of collagen fibres and fibroblast cords in the dermis and hypodermis. Groups of eccrine sweat glands were observed in the reticular dermis of C. didactylus, B. variegatus, T. tetradactyla and only in the hypodermis of Cyclopes didactylus.

One Size Does Not Fit All: Diversifying Immune Function in the Skin.

Our body's most outward facing epithelial barrier, the skin, serves as the frontline defense against myriad environmental assailants. To combat these motley threats, the skin has evolved a sophisticated immunological arsenal. In this article, I provide an overview of the skin's complex architecture and the distinct microniches in which immune cells reside and function. I review burgeoning literature on the synchronized immune, stromal, epithelial, and neuronal cell responses in healthy and inflamed skin. Next, I delve into the distinct requirement and mechanisms of long-term immune surveillance and tissue adaptation at the cutaneous frontier. Finally, by discussing the contributions of immune cells in maintaining and restoring tissue integrity, I underscore the constellation of noncanonical functions undertaken by the skin immune system. Just as our skin's immune system benefits from embracing diverse defense strategies, so, too, must we in the immunology research community support disparate perspectives and people from all walks of life.

Structural and functional differences in skin of colour.

The term 'skin of colour' (SOC), refers to individuals of African, Latinx, Asian, Native Hawaiian, Pacific Islander and Indigenous descent. These individuals typically have darker skin tones compared with white individuals and they often present with unique disorders of the skin or with common disorders that have a unique appearance. Certain skin conditions commonly associated with SOC patients, in contrast to individuals with lighter skin tones, are explained by structural and functional differences between this population and the white population. Variations in functional differences between these two groups are dependent on structural differences in melanosomes, stratum corneum, epidermis and dermis. Understanding the structural distinctions between white populations and SOC populations will provide insight into common disorders in SOC patients, including hyperpigmentation, hypopigmentation, dry skin, scaliness, xerosis, sensitive skin and keloids. Furthermore, understanding structural and functional skin difference will encourage more research regarding aetiology of disease and therapeutic interventions.

Automatic algorithm for the characterization of sweat ducts in a three-dimensional fingerprint.

In this study, an automatic algorithm has been presented based on a convolutional neural network (CNN) employing U-net. An ellipsoid and an ellipse were applied for approximation of a three-dimensional sweat duct and en face sweat pore at the different depths, respectively. The results demonstrated that the length and the diameter of the ellipsoid can be used to quantitatively describe the sweat ducts, which has a potential for estimating the frequency of resonance in millimeter (mm) wave and terahertz (THz) wave. In addition, projection-based sweat pores were extracted to overcome the effect that the diameters of en face sweat pores depend on the depth. Finally, the projection-based image of sweat pores was superposed with a maximum intensity projection (MIP)-based internal fingerprint to construct a hybrid internal fingerprint, which can be applied for identification recognition and information encryption.

Lens fluorescence and skin fluorescence in the Copenhagen Twin Cohort Eye Study: Covariates and heritability.

Lens and skin fluorescence are related to the systemic accumulation of advanced glycation end products, which is accelerated in diabetes. We have examined lens fluorescence and skin fluorescence in healthy adult twins. The study enrolled twins aged median 59 years from a national population-based registry. Diabetic individuals were excluded from analysis. The interrelatedness between fluorescence parameters and relations between fluorescence and age, current HbA1c and smoking pack years were examined using correlation tests and mixed model linear regression analyses. Broad-sense heritability was analyzed and compared for lens fluorescence, skin fluorescence and HbA1c. Lens fluorescence and skin fluorescence were crudely interrelated (R = 0.38). In linear regression analyses, age explained a larger fraction of the variance in lens fluorescence (R2 = 32%) than in skin fluorescence (R2 = 20%), whereas HbA1c explained smaller variance fractions (R2 = 3% and 8%, respectively) followed by smoking pack years (4% and 3%, respectively). In multivariate analyses, age, HbA1c and smoking pack years combined explained more of the variance in lens fluorescence (R2 = 35%) than in skin fluorescence (R2 = 21%), but the influence of HbA1c on lens fluorescence was not statistically significant (p = .2). Age-adjusted broad-sense heritability was 85% for lens fluorescence, 53% for skin fluorescence and 71% for HbA1c in best fitting heritability models. Both fluorescence parameters increased with age, current glycemia and cumulative smoking. Lens fluorescence was found to be a predominantly heritable trait, whereas skin fluorescence was more influenced by environmental factors and closer related to current glycemia. The results suggest that skin fluorophores have a faster turn-over than lens fluorophores.

Distribution, fine structure, and three-dimensional innervation of lamellar corpuscles in rat plantar skin.

Lamellar corpuscles function as mechanoreceptors in the skin, composed of axon terminals and lamellae constructed by terminal Schwann cells. They are classified into Pacinian, Meissner, and simple corpuscles based on histological criteria. Lamellar corpuscles in rat dermal papilla cells have been reported; however, the morphological aspects have yet to be thoroughly investigated. In the present study, we analyzed the enzyme activity, distribution, fine structure, and three-dimensional innervation of lamellar corpuscles in rat plantar skin. The lamellar corpuscles exhibiting non-specific cholinesterase were densely distributed in rat footpads, evident as notable skin elevations, especially at the apex, the highest portion of the ridges in each footpad. In contrast, only a few lamellar corpuscles were found in other plantar skin areas. Lamellar corpuscle was considered composed of a flat axon terminal Schwann cell lamellae, which were roughly concentrically arranged in the dermal papilla. These histological characteristics correspond to those of the simple corpuscle. Moreover, the axon tracing method revealed that one trunk axon innervated several simple corpuscles. The territory of the trunk axons overlapped with each other. Finally, the animals' footprints were analyzed. During the pausing and walking phases, footpads are often in contact with the floor. These results demonstrate that the type of lamellar corpuscles in the dermal papillae of rat plantar skin is a simple corpuscle and implies that their distribution pattern in the plantar skin is convenient for efficient sensing and transmission of mechanical stimuli from the ground.

Developmental genetics of color pattern establishment in cats.

Intricate color patterns are a defining aspect of morphological diversity in the Felidae. We applied morphological and single-cell gene expression analysis to fetal skin of domestic cats to identify when, where, and how, during fetal development, felid color patterns are established. Early in development, we identify stripe-like alterations in epidermal thickness preceded by a gene expression pre-pattern. The secreted Wnt inhibitor encoded by Dickkopf 4 plays a central role in this process, and is mutated in cats with the Ticked pattern type. Our results bring molecular understanding to how the leopard got its spots, suggest that similar mechanisms underlie periodic color pattern and periodic hair follicle spacing, and identify targets for diverse pattern variation in other mammals.

Regulatory mechanism of oral mucosal rete peg formation.

Rete pegs are finger-like structures that are formed during the development and wound healing process of the skin and oral mucosa, and they provide better mechanical resistance and nutritional supply between the epithelium and dermis. An increasing number of studies have shown that rete pegs have physiological functions, such as resisting bacterial invasion, body fluid loss, and other harmful changes, which indicate that rete pegs are important structures in natural skin and oral mucosa. Although a great deal of progress has been made in scaffold materials and construction methods for tissue-engineered skin and oral mucosa in recent years, construction of the oral mucosa with functional rete pegs remains a major challenge. In this review, we summarized current research on the progress on formation of rete pegs in human oral mucosa as well as its molecular basis and regulatory mechanism, which might provide new ideas for functional construction of tissue-engineered skin and oral mucosa.