Regional thickness of facial skin and superficial fat: Application to the minimally invasive procedures

Various recently introduced minimally invasive treatment modalities are now widely used for enhancing the aging face. In a special, filler is used to increase the volume of tissue, and so understanding the regional thickness and distribution of the facial superficial fat is essential for optimizing minimally invasive procedures. The aim of this study was to establish the overall facial skin and superficial fat thicknesses using a three‐dimensional (3D) scanning system. From 53 adult Korean and Thai embalmed adult cadavers, the undissected and serially‐dissected facial specimens were scanned and reconstructed. The facial skin and superficial fat thicknesses on seven facial regions were calculated from the superimposed images. The facial skin tended to become thicker in the order of the radix and dorsum, and the temple, supraorbital, forehead, perioral, cheek, and infraorbital areas. The skin was thinnest at radix and dorsum (1.51 ± 0.55 mm), and thickest in infraorbital region (1.97 ± 0.84 mm). The facial superficial fat thickness tended to increase in the order of the radix and dorsum, supraorbital, forehead, temple, cheek, infraorbital, and perioral regions. The superficial fat was thinnest at the radix and dorsum (1.61 ± 1.07 mm), and thickest in the perioral region (5.14 ± 3.31 mm). The facial superficial fat thickness tended to increase in the order of the radix and dorsum, supraorbital, forehead, temple, cheek, infraorbital, and perioral regions. The present findings indicate that 3D scanning system can yield crucial anatomical information about depths of the facial skin and superficial fat layers for utilization in various clinical procedures. Clin. Anat. 32:1008–1018, 2019. © 2019 Wiley Periodicals, Inc.     

Epidermal and papillary dermal characteristics of the bowhead whale (Balaena mysticetus)

Skin samples from most body regions of the bowhead whale were examined. The epidermis is 2.7 to 50 times thicker than that reported in other cetaceans with both regional and individual variations in thickness. The thinnest areas examined (1 mm) occur on the eyelid margins and the thickest (25 mm) occur on the lower jaw. A distinctive parakeratotic stratum corneum with a thick underlying stratum spinosum (without a stratum granulosum) extends over the entire body surface. From a few dozen to several hundred epidermal lesions are present on all whales studied. A typical stratum basale of germinative keratinocytes (with melanocytes in pigmented areas) rests upon a well-defined basal lamina. Epidermal rod arrays arise from the basal keratinocytes which cover highly elongated dermal papillae and extend to the epidermal surface through the distal stratum spinosum and the stratum corneum. At least four diatom genera occur on and in the stratum corneum and lesion areas of different whales. The superficial dermis consists of a papillary layer with long (up to 13 mm) dermal papillae interdigitating with the epidermis from a basal area that is 2-4 mm in thickness. The number of dermal papillae per mm2 varies inversely with the thickness of the epidermis. Large diameter, sensory papillae packed with tortuous, highly elongated, encapsulated nerve end organs also interdigitate with the thin epidermal areas of the ventral surface of the rostrum, the upper and lower lip margins, and the upper and lower eyelid margins. Scattered, single, stiff hairs emerge from the skin only in specific, pigmented regions of the head.     

Observations on the actual structural conditions in the stratum superficiale dermidis of porcine ear skin, with special reference to its use as model for human skin.

The results obtained from the outer ear skin of female pigs (German Landrace) by light microscopy (LM), transmission electron microscopy (TEM), and cryo scanning electron microscopy (cryo SEM) methods, in particular relying on careful and artefact-free tissue processing, exhibited that the stratum superficiale dermidis of the auricle had a very homogeneous and compact construction, especially in one area (central dorsum auriculae). Based upon the important measurements made [average thickness of stratum superficiale dermidis: 94 (+/-16) microm, region A: 81 (+/-10); average thickness of collagen fibre bundles: 12 (+/-2) microm, region A: 13 (+/-0.5); average density of subepidermal capillaries: 3134 (+/-459) loops/cm2, region A: 3497 (+/-247)], this impression was confirmed by low standard deviations for all parameters, in comparison to marginal locations studied. The capillary system present was analysed by LM and TEM for specific structural features, whereby it generally compared to the microvasculature in human skin. Moreover, a regular pattern of diffusion-relevant punctiform contacts of the capillary loop apex with the epidermal basement membrane became obvious. Cryo SEM, particularly offering the advantages of dispensation of chemical fixation, dehydration and solvents during processing, highlighted delicate structures without shrinkage and without loss of soluble sample components. Thus rather real spatial conditions in the region of the epidermo-dermal junction and the upper dermis were visualized, whereby very regular arrangements of the structures present became obvious. This pertained also to a correct demonstration of all components of the epidermal basement membrane, in particular the lamina lucida. In addition, the water-based stable character of the entire stratum superficiale dermidis could be emphasized as a basic feature for controlled diffusion processes.     

Influence of cutaneous nerves on keratinocyte proliferation and epidermal thickness in mice

We evaluated the influence of skin innervation on the epidermis in mice. The rich innervation of skin was demonstrated by immunocytochemistry with protein gene product 9.5, a ubiquitin carboxy hydrolase. Protein gene product-immunoreactive nerve fibers were in the epidermis, subepidermal plexus, dermal nerve trunks, and nerve terminals around sweat glands. Effects of denervation on the plantar surface of the hind foot was assessed by comparing the thickness of the epidermis, which was innervated by the sciatic nerve. Within 48 h after sectioning of the sciatic nerve, protein gene product (+)-nerves in the territory of the sciatic nerve were completely degenerated. There was a significant thinning of the denervated epidermis 72 h post-transection (30.5+/-1.1 vs 41.4+/-2.9 microm, 74+/-4% of the control side). The reduction in epidermal thickness persisted when skin remained denervated (69-75% of the control side). Incorporation of bromodeoxyuridine was reduced 24 h after denervation (71+/-6% of the control side). Reduction in bromodeoxyuridine-incorporation was most pronounced within 48 h after denervation (19+/-6% of the control side). Therefore, the reduction in bromodeoxyuridine-labeling followed a similar temporal course as the thinning of the epidermis (25-50%). Both epidermal thinning and reduced bromodeoxyuridine-labeling were reversed by epidermal reinnervation three months after denervation. Patterns of keratinocyte differentiation and programmed cell death were unaffected by skin denervation. These findings are consistent with the notion that skin innervation exerts influence on the proliferation of keratinocytes and the thickness of the epidermis, and offers a new look at the interaction between nociceptive nerves and their innervated targets.     

Tissue response to single-polymer fibers of varying diameters: evaluation of fibrous encapsulation and macrophage density

An in vivo study was conducted to assess the sensitivity of fibrous capsule thickness and macrophage density to polymer fiber diameter. Single polypropylene fibers of diameters ranging from 2.1 to 26.7 microm were implanted in the subcutaneous dorsum of Sprague-Dawley rats. Results at 5 weeks demonstrated reduced fibrous capsule thickness for small fibers. Capsule thickness was 0.6 (+/-1.8) microm, 11.7 (+/-12.0) microm, 20.3 (+/-11.6) microm, and 25.5 (+/-10.0) microm for fibers in the ranges of 2.1 to 5.9, 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 microm, respectively. Fibers very near to blood vessels had smaller capsules than did those with local vasculature further away. The macrophage density in tissue with fiber diameters 2.1 to 5.9 microm (23.03 +/- 8.67%) was comparable to that of unoperated contralateral control skin (18.72+/-10.06%). For fibers with diameters in the ranges of 6.5 to 10.6, 11.1 to 15.8, and 16.7 to 26.7 microm, macrophage densities were 33.90+/-13.08%, 34.40+/-15.77%, and 41.68+/-13.98%, respectively, all of which were significantly larger (p<0.002) than that for the control. The reduced fibrous capsule thickness and macrophage density for small fibers (<6 microm) compared with large fibers could be due to the reduced cell-material contact surface area or to a curvature threshold effect that triggers cell signaling. A next step will be to extend the analysis to meshes to evaluate fiber-spacing effects on small-fiber biomaterials.     

The membranous layer of superficial fascia: evidence for its widespread distribution in the body

A discrete membranous layer, “stratum membranosum”, in human subcutaneous tissue is classically described as confined to the lower anterior abdominal wall and perineum and referred to as Scarpa’s and Colles’ fasciae, respectively. Evidence for its existence elsewhere in the body is scanty and therefore the present study was undertaken. Dissection of six embalmed adult cadavers, along with ultrasound imaging on four living subjects, were carried out to determine the existence, topography, and thickness of the membranous layer of superficial fascia in different regions of the body. In all six cadavers, a continuous layer of fibrous membrane in the superficial fascia was found consistently in all the dissected regions of the body and was also confirmed by ultrasonography. The arrangement and thickness of this membranous layer varied according to body region, body surface, and gender. It was thicker in the lower than in the upper extremity, on the posterior than anterior aspect of the body, and in females than in males. The mean thickness of the membranous layer ranged from 39 to 189 μm, being thickest in the leg and thinnest over the dorsum of the hand. The membranous layer was observed to have two or even three components in regions such as the breast, back, thigh, and arm and was seen to split, forming special compartments around subcutaneous major veins of upper and lower extremities, with fibrous septa extending to attach to the vessel wall. Functionally, the membranous superficial fascia may play a role in the integrity of the skin and support for subcutaneous structures particularly veins, by ensuring their patency. Understanding the topographic anatomy of this fascial layer may help explain body-contour deformities and provide the anatomic basis for surgical correction.     

Tissue response to microfibers of different polymers: polyester,polyethylene, polylactic acid,and polyurethane

Tissue response to single polymer microfibers of polyester (PET), polyethylene (PE), poly(L-lactic acid) (PLA), and polyurethane (PU) was assessed using a rat subcutaneous model. Fibers of diameters ranging from 1 to 15 microm were aligned parallel to each other on polycarbonate frames and implanted in the subcutaneous dorsum in the subscapular region. After 5 weeks of implantation, fibrous capsule thickness was significantly less for fibers of diameters 1-5 than for those of 11-15 microm for all polymers tested. For PET and PU, 75.0 and 71.4% respectively of the 1-5 microm fibers had no capsule, while for PE and PLA only 45.5 and 56.3% respectively had no capsule. For 1-5 microm fibers, PE had significantly thicker capsules than PET and PU. Reducing fiber diameters from 6-10 to 1-5 microm induced a greater reduction in capsule thickness than changing polymers among PET, PE, and PLA. PU showed the least encapsulation of all polymers, demonstrating significantly thinner capsules than PET, PE, and PLA for 6-10 and 11-15 microm fibers.     

The skin structures and their role in the thermoregulation of the South American fur seal (Arctocephalus australis)

The skin of the South American fur seal (Arctocephalus australis) is important for animal thermoregulation in both terrestrial and aquatic environments. Skin tissue samples were collected from A. australis for microscopic analysis and were related to anatomical references. The aim of this study was to describe the skin morphology, as well as to suggest the major anatomical regions and skin components involved in the thermoregulation of this species. Using light microscopy, the skin of six animals was examined based on histological, morphometric, and immunohistochemical criteria. Hair follicle morphology was examined using scanning electron microscopy. The skin was classified as either thick or thin based on its epidermal thickness. The thin epidermis regions had more abundant hair follicles, as well as high pigmentation, whereas the thick epidermis regions had very pigmented epidermal layers. Pigmentation of hair and skin is fundamental for protection against ultraviolet rays; moreover, hair is important in preventing abrasion, and provides an insulating layer against the external environment, which can be much colder than body temperature. Furthermore, the dermis is well vascularized, especially the superficial dermis. All regions of the skin have adaptations for maintaining the animal's condition in both terrestrial and aquatic environments. Among the studied regions, the interdigital region from hindflipper showed important morphological characteristics related to thermoregulation, such as having an epidermis of intermediate thickness, a dermis with a small number of hairs, a large amount of blood vessels, and sweat glands with large lumens, indicating that heat exchange in this region may be faster.     

Epidermis promotes dermal fibrosis: role in the pathogenesis of hypertrophic scars

Hypertrophic scarring is a pathological process characterized by fibroblastic hyperproliferation and by excessive deposition of extracellular matrix components. It has been hypothesized that abnormalities in epidermal-dermal crosstalk explain this pathology. To test this hypothesis, a tissue-engineered model of self-assembled reconstructed skin was used in this study to mimic interactions between dermal and epidermal cells in normal or pathological skin. These skin equivalents were constructed using three dermal cell types: normal wound (Wmyo) or hypertrophic wound (Hmyo) myofibroblasts and normal skin fibroblasts (Fb). Epidermis was reconstructed with normal skin keratinocytes (NK) or hypertrophic scar keratinocytes (HK). In the absence of keratinocytes, Hmyo formed a thicker dermis than Wmyo. When seeded with NK, the dermal thickness of Hmyo (121.2 +/- 31.4 microm vs 196.2 +/- 27.8 microm) and Fb (43.7 +/- 7.1 microm vs 83.6 +/- 16.3 microm) dermis was significantly (p < 0.05) reduced, while that of Wmyo (201.5 +/- 15.7 microm vs 160.7 +/- 21.1 microm) was increased. However, the presence of HK always induced significantly thicker dermis formation than observed with NK (Wmyo: 238.8 +/- 25.9 microm; Hmyo: 145.5 +/- 22.4 microm; Fb: 74.2 +/- 11.2 microm). These results correlated with collagen and MMP-1 secretion and with cell proliferation, which were increased when keratinocytes were added, except for the collagen secretion of Hmyo and Fb in the presence of NK. The level of dermal apoptosis was not different when epidermis was added to the dermis (<1% in each category). These observations strongly suggest that hypertrophic scar keratinocytes play a role in the development of pathological fibrosis by influencing the behaviour of dermal cells.     

The structural design of the bat wing web and its possible role in gas exchange

The structure of the skin in the epauletted fruit bat (Epomophorus wahlbergi) wing and body trunk was studied with a view to understanding possible adaptations for gas metabolism and thermoregulation. In addition, gas exchange measurements were performed using a respirometer designed for the purpose. The body skin had an epidermis, a dermis with hair follicles and sweat glands and a fat-laden hypodermis. In contrast, the wing web skin was made up of a thin bilayered epidermis separated by a connective tissue core with collagen and elastic fibres and was devoid of hair follicles and sweat glands. The wings spanned 18-24 cm each, with about 753 cm2 of surface exposed to air. The body skin epidermis was thick (61 +/- 3 microm, SEM), the stratum corneum alone taking a third of it (21 +/- 3 microm). In contrast, the wing web skin epidermis was thinner at 9.8 +/- 0.7 microm, with a stratum corneum measuring 4.1 +/- 0.3 microm (41%). The wing capillaries in the wing web skin ran in the middle of the connective tissue core, with a resultant surface-capillary diffusion distance of 26.8 +/- 3.2 microm. The rate of oxygen consumption (VO2) of the wings alone and of the whole animal measured under light anaesthesia at ambient temperatures of 24 masculineC and 33 masculineC, averaged 6% and 10% of the total, respectively. Rate of carbon dioxide production had similar values. The membrane diffusing capacity for the wing web was estimated to be 0.019 ml O2 min(-1) mmHg(-1). We conclude that in Epomophorus wahlbergi, the wing web has structural modifications that permit a substantial contribution to the total gas exchange.     

Guinea pig and rabbit model for the histological evaluation of permanent percutaneous implants

The object of this study was to develop a small experimental animal model for a systematic study of the interfacial phenomena between percutaneous implants and skin. Plasma-sprayed and dense hydroxyapatite test implants were inserted into the tibia and dorsum of guinea pigs and into the tibia and on the cranium of rabbits. At preselected periods, the animals were killed and the implants with their surrounding tissues were processed histologically. The results revealed that the tibia and cranial implants had healed uneventfully. The epidermis showed no tendency to grow down into the dermis, but appeared to form a stable junction with the implant surface. Around the dorsal implants, the epidermis migrated downwards and most of these implants were lost 6 weeks after insertion. It was concluded that the guinea pig and the rabbit were a suitable model for studying the pathophysiology of percutaneous wound healing and that the implant location is an important factor for percutaneous implant success.     

眼睑皮肤厚度及其与单睑和重睑的相关性

目的积累眼睑的局部解剖学数据,为临床眼科手术等提供资料。方法做3条垂线,将尸体睑裂均分为4等份。沿3条垂线测量34具头颅标本下睑缘下方2 mm和上睑缘上方3 mm、6 mm的各点皮肤厚度。将上述各项数据按单、重睑分类并行统计学比较。结果单睑的上睑皮肤较重睑厚。单、重睑样本的下睑皮肤均显著薄于上睑皮肤。结论较薄的上睑皮肤可能有利于重睑的形成;较薄的下睑皮肤是眼袋形成的重要结构基础。     

Mechanical forces induce scar remodeling. Study in non-pressure-treated versus pressure-treated hypertrophic scars.

Reparative process of second and third degree burns usually results in hypertrophic scar formation that can be treated by pressure. Although this method is efficient, its mechanisms of action are not known. In this work, we have studied the histological organization of hypertrophic scars submitted to pressure. Skin biopsies were performed 2 to 7 months after the onset of treatment in two adjacent regions of the scar, non-pressure- or pressure-treated and analyzed by immunohistochemistry and transmission electron microscopy for extracellular matrix organization and cellular morphology. In non-pressure-treated regions, fibrillin deposits did not present the classical candelabra-like pattern under epidermis and were reduced in dermis; in pressure-treated regions the amount was increased compared to non-pressure-treated regions but the organization was still disturbed. In non-pressure-treated regions, elastin was present in patch deposits; in pressure-treated regions elastin formed fibers, smaller than in normal dermis. Tenascin was present in the whole dermis in non-pressure-treated regions, whereas in pressure-treated regions it was observed only under epidermis and around vessels, as in normal skin. alpha-Smooth muscle actin-expressing myofibroblasts were absent in normal skin, present in large amounts in non-pressure-treated regions, and almost absent in pressure-treated regions. The disturbed ultrastructural organization of dermal-epidermal junction observed in non-pressure-treated regions disappeared after pressure therapy; typical features of apoptosis in fibroblastic cells and morphological aspects of collagen degradation were observed in pressure-treated regions. Our results show that, in hypertrophic scars, pressure therapy restores in part the extracellular matrix organization observed in normal scar and induces the disappearance of alpha-smooth muscle actin-expressing myofibroblasts, probably by apoptosis. We suggest that the pressure acts by accelerating the remission phase of the postburn reparative process.     

尿道下裂尿道成形材料的Masson染色组织学特点

目的　通过观察尿道下裂尿道成形材料的组织学特点,指导手术材料的选择。  方法　收集2011年9月-2013年10月中山大学附属第一医院小儿外科重型尿道下裂患者阴茎阴囊皮肤标本共20例,每例均取包皮内板、阴茎体腹侧皮肤、阴囊中隔皮肤、阴囊周边皮肤四份标本,经福尔马林固定,石蜡包埋,超薄切片,Masson染色,置于高倍显微镜下由非本实验研究者利用正立显微成像系统随机拍取5个视野,由研究者观察并计算毛囊、皮脂腺、皮下血管密度以及测量皮肤厚度。  结果　毛囊及皮脂腺密度比较：阴囊中隔皮肤＜阴囊周边皮肤（P＜0.05）,而包皮内板及阴茎体腹侧皮肤未见毛囊及皮脂腺。血管密度比较：包皮内板＞阴茎体腹侧皮肤＞阴囊中隔皮肤＞阴囊周边皮肤（各组比较P＜0.05）。皮肤厚度比较：包皮内板＜阴囊周边皮肤＜阴茎体腹侧皮肤＜阴囊中隔皮肤（各组比较P＜0.05）。  结论　包皮内板及阴茎体腹侧的皮肤是理想的尿道成形材料,材料不足时可适当使用阴囊中隔皮肤,阴囊周边皮肤一般不应用于尿道成形。     

Three-month, zero-order piroxicam release from monodispersed double-walled microspheres of controlled shell thickness

Double-walled microspheres represent an increasingly important class of drug delivery devices that provide enhanced control of drug delivery schedules. Clearly, the overall particle size and shell thickness are important parameters in modulating the drug release rates. Precision particle fabrication technology has been used to fabricate double-walled microspheres of predefined uniform diameters of 40-60 microm exhibiting a poly(D,L-lactide-co-glycolide) (PLG) core and poly(L-lactide) (PL) shell of controllable thickness from approximately 2 to 10 microm. The release of a model small-molecule drug, piroxicam, from uniform microspheres of pure PLG and PL is compared to the release from double-walled microspheres exhibiting different PL shell thicknesses. The presence of the PL shell enveloping a PLG core essentially eliminated the initial "burst" of piroxicam that was observed when the drug was released from pure PLG microspheres. In addition, increasing the PL shell thickness shifted the release profile from a biphasic shape for pure PLG microspheres to zero-order piroxicam release over 3 months for the thickest (approximately 10 microm) PL shell.     

Thickness of the stratum corneum of the volar fingertips

The thickness of the stratum corneum was measured by optical coherence tomography at the center and sides of the tactile elevations of all fingers in 87 healthy volunteers and 18 people with diabetes who performed regular glucose self-control. The cornified epidermis was thickest at the thumbs, and thickness decreased toward the little finger. The cornified epidermis was thinner at the sides of the tactile elevations than at the center, and it was thinner in women than in men. In people with diabetes, the cornified epidermis of the fingers most frequently used for capillary blood sampling was not conspicuously thickened.     

Isolation and characterization of migratory human skin dendritic cells.

A method is described to isolate and characterize human skin dendritic cells (DC). This method is based on the migratory capacities of these cells. The cells migrated 'spontaneously' out of split-skin explants into the medium during a 24-h culture period and contained up to 75% CD1a+ cells. After removal of co-migrated T cells and macrophages, the highly enriched (> 95% CD1a+) DC showed potent allo-antigen-presenting capacities. About 25% of the CD1a+ cells were also positive for the dermal DC marker CD1b, whereas only 15-20% of the cells contained Birbeck granules, the characteristic cell organelle of the epidermal Langerhans cell. Before culture, CD1a+ DC were observed on cryostat sections not only in the epidermis but also in the dermis. After culture, the number of CD1a+ cells in both epidermis and dermis had decreased. Not all the cells had migrated during the culture period; some CD1a+ cells could still be detected in the epidermis and dermis after culture. Thus, using this method, potent allo-stimulating CD1a+ cells, migrating from both epidermis and dermis, can be obtained without the use of enzymes.     

Morphological Changes in Skin Glands During Development in Rhinella Arenarum (Anura: Bufonidae)

Avoiding predation is critical to survival of animals; chemical defenses represent a common strategy among amphibians. In this study, we examined histologically the morphology of skin glands and types of secretions related to chemical skin defense during ontogeny of Rhinella arenarum. Prior to metamorphic climax the epidermis contains typical bufonid giant cells producing a mucous substance supposedly involved in triggering a flight reaction of the tadpole school. An apical layer of alcianophilic mucus covers the epidermis, which could produce the unpleasant taste of bufonid tadpoles. Giant cells disappear by onset of metamorphic climax, when multicellular glands start developing, but the apical mucous layer remains. By the end of climax, neither the granular glands of the dorsum nor the parotoid regions are completely developed. Conversely, by the end of metamorphosis the mucous glands are partially developed and secrete mucus. Adults have at least three types of granular glands, which we designate type A (acidophilic), type B (basophilic) and ventral (mucous). Polymorphic granular glands distribute differently in the body: dorsal granular glands between warts and in the periphery of parotoids contain protein; granular glands of big warts and in the central region of parotoids contain catecholamines, lipids, and glycoconjugates, whereas ventral granular glands produce acidic glycoconjugates. Mucous glands produce both mucus and proteins. Results suggest that in early juveniles the chemical skin defense mechanisms are not functional. Topographical differences in adult skin secretions suggest that granular glands from the big warts in the skin produce similar toxins to the parotoid glands. Anat Rec, 299:141–156, 2016. © 2015 Wiley Periodicals, Inc.