Facial soft tissue changes after maxillary impaction and mandibular advancement in high angle class II cases

The aim of this study was to determine the vertical and anteroposterior alterations in the soft, the dental and the skeletal tissues associated with the facial profile after Le Fort I maxillary impaction in conjunction with sagittal split osteotomy for mandibular advancement performed in patients with a high angle Class II skeletal deformity.The study population consists of 21 patients (11 females and 10 males, mean age 24.5±1.6 years) who underwent Le Fort I maxillary impaction in conjunction with sagittal split osteotomy for mandibular advancement. Lateral cephalograms were obtained prior to the surgery and 1.3±0.2 years postoperatively. Wilcoxon test was performed to compare the pre- and postsurgical cephalometric measurements. Pearson correlation test was carried out to determine the relative changes in skeletal, dental and the facial soft tissues.The insignificant decrease in the nasolabial angle was correlated with the significant decrease in the vertical position of the nose due to the nasal protraction noticed after bimaxillary surgery. The retraction of both the upper lip and the upper incisors was correlated with the insignificant decrease in the columella-lobular angle. The insignificant decrease in both the vertical height of the mandibular B point and the lower incisors was correlated with the insignificant decrease in vertical height of the soft tissue pogonion, attributable to the resulting superior movement of the soft tissues of the chin and the counter clockwise rotation of the mandible after maxillary impaction and bilateral sagittal split osteotomy, respectively.Le Fort I maxillary impaction in conjunction with mandibular sagittal split osteotomy for mandibular advancement significantly affected the vertical and anteroposterior positions of the maxilla and the mandible, respectively. When performed in combination, these surgical techniques may efficiently alter the position of upper incisor and the nasal position in both vertical and anteroposterior directions. Bimaxillary orthognathic surgery seems to be an efficient method for obtaining satisfactory results in the appearance of the soft, the dental and the skeletal tissues associated with the facial profile in patients with high angle Class II skeletal deformity.     

四川正常成人X线头影测量研究Ⅱ

目的 观察颜面软组织与其深面的骨性结构在构成容貌基本特征上的关系及不同地区人群、不同人种容貌之间的差异。方法 对四川籍120例(男女各半)18岁正常(牙合)汉族人按Wylie及Burstone等的方法测量硬组织径线和按Burstone及Legan等的方法测量软组织径线共55项;对各项指标测量数据进行统计学处理。观察性差、不同地区人群及国人同美国白人之间的差异。结果 发现各项指标测量值男性均大于女性,但在牙、颌、面结构间的彼此配合的关系上、颅颌面在侧貌突度及面高比值方面两性之间没有显著意义的差异,唯女性软组织侧貌比男性相对较直;同北方人群的资料比较,发现人群的颅面骨骼测量值大于四川人群,四川人群面部侧貌突度比北方人大,男性尤甚;国人与美国白人之间在侧貌突度上差异显著,白人前额与颏部比国人明显前突,国人上颌、唇部比白人显著靠前。结论 颅颌面骨骼是构成容貌基本特征的基础;但骨骼表面的软组织在构成容貌特征上亦有重要意义;软组织与其深面的硬组织之间存在着不一致性。     

Nasal Septal Deviation and Facial Skeletal Asymmetries

During ontogeny, the nasal septum exerts a morphogenetic influence on the surrounding facial skeleton. While the influence of the septum is well established in long snouted animal models, its role in human facial growth is less clear. If the septum is a facial growth center in humans, we would predict that deviated septal growth would be associated with facial skeletal asymmetries. Using computed tomographic (CT) scans of n = 55 adult subjects, the purpose of this study was to test whether there is a correlation between septal deviation and facial asymmetries using three‐dimensional (3D) geometric morphometric techniques. We calculated deviation as a percentage of septal volume relative to the volume of a modeled non‐deviated septum. We then recorded skeletal landmarks representing the nasal, palatal, and lateral facial regions. Landmark data were superimposed using Procrustes analysis. First, we examined the correlation between nasal septal deviation and the overall magnitude of asymmetry. Next, we assessed whether there was a relationship between nasal septal deviation and more localized aspects of asymmetry using multivariate regression analysis. Our results indicate that while there was no correlation between septal deviation and the overall magnitude of asymmetry, septal deviation was associated with asymmetry primarily in the nasal floor and the palatal region. Septal deviation was unassociated with asymmetries in the lateral facial skeleton. Though we did not test the causal relationship between nasal septal deviation and facial asymmetry, our results suggest that the nasal septum may have an influence on patterns of adult facial form. Anat Rec, 299:295–306, 2016. © 2016 Wiley Periodicals, Inc.     

6～12岁双生子女童头影测量中H平面的环境和遗传作用分析

目的 探讨环境和遗传因素在混合牙列期对软组织H平面的影响，为确立牙齿的正确矫治计划提供理论依据。 方法 测量6～12岁183对双生子女童的头颅侧位片，利用双生子法得出生长发育过程中环境和遗传因素对颅面软组织侧貌产生的影响。 结果 H1软组织鼻根点、H2鼻顶点、H4鼻下点、H9下唇凹点、H10软组织颏下点均能够检测到受环境因素的影响，而H9下唇凹点受环境和遗传因素的双重影响。 结论 上下唇部可以检测出受环境因素的影响，下唇凹点受到环境和遗传因素的共同影响。     

四川正常He成人X线头影测量研究Ⅰ

目的：观察颜面软组织与其深面的骨性结构在构成容貌基本特征上的关系及不同地区人群、不同人种容貌之间的差异。方法：对四川籍120例（男女各半）18岁以上正常He汉族人按Downs及Steiner等的方法进行18种骨骼和牙齿的角度测量。按Burstone等的方法进行软组织的16处角度测量分析，并将测量结果与北京、哈尔滨等地人群的资料进行比较以及同美国白人资料比较。结果：骨性测量显示男性上颌骨位置比女性靠前、软组织测量显示男性侧貌突变大于女性，提示颅颌面软组织与其深面的骨性结构之间的不一致，四川人和北京、哈尔滨等地人群相比，颜面侧貌突变明显大于北方人群，国人与美国白人相比，面部侧貌轮廓显著前突，而白人前额和额部比国人明显前突，形成显著差异。结论；在作矫形治疗或整形美容时应充分考虑地区因素，同时还要考虑患者及当地人们的审美观，国外的体质资料更不能盲目引用。     

Variation in the Developmental and Morphological Interaction Between the Nasal Septum and Facial Skeleton

While the nasal septum exerts a morphogenetic influence on the facial skeleton, there is evidence that this relationship is highly variable. To better appreciate the precise role of the septum, it is important understand the variable interaction between the septum and surrounding skeleton during ontogeny. Here we analyzed nasal septal and facial skeletal postnatal phenotypic variation using cross‐sectional samples of C3H/HeJ and C57BL/6J mice. Initial observations indicated between‐strain variation in the magnitude of septal deviation, suggesting differences in septal and facial skeletal interaction. We examined whether variation in septal deviation is due to ontogenetic differences in septal size, or whether variation in facial skeletal growth imposes spatial constraints on the septum. Using microCT we quantified septal size and deviation, and collected coordinate landmark data, which we analyzed using geometric morphometrics. C3H/HeJ mice were significantly more deviated than C57BL/6J during development. We found no differences in septal size between the two strains. However, while both strains exhibited an ontogenetic increase in snout length, C3H/HeJ mice exhibited a non‐allometric reduction in nasal bone length. This appears to be influenced by between‐strain variation in the spatial relationship between the nasal septum and nasofrontal suture. Unlike C57BL/6J mice, the C3H/HeJ nasal septum is positioned anterior to the nasofrontal suture potentially limiting an early direct influence of septal growth (e.g., through interstitial expansion) on sutural growth. Ultimately, our results underscore that while the septum is a key facial growth center, its precise influence on facial growth varies even in narrow morphological and taxonomic ranges. Anat Rec, 299:730–740, 2016. © 2016 Wiley Periodicals, Inc.     

The midline craniofacial skeleton in holoprosencephalic fetuses.

Craniofacial skeletal development in eight human holoprosencephalic fetuses from second trimester abortions were examined by radiography and histology. The whole spectrum of associated facial malformations from anophthalmia through cyclopia, ethmocephaly, cebocephaly, and median cleft lip to short philtrum was represented. Cases with the most severe facial malformations also had the most severely affected facial skeleton. In the facial skeleton, the premaxilla was most often affected; it was absent in seven cases and malformed in the one with only a short philtrum. This and other facial skeletal malformations can be explained as abnormal fusion of the facial bones because of defective development of the nasal cartilage. The occipital bones were normal, but the basicranial skeleton anterior to the spheno-occipital junction was affected in all cases. The findings support the hypothesis that the facial malformations in holoprosencephaly result from disturbance in embryonal life of the mesoderm at the rostral end of the notochord.     

DR组织均衡技术在低剂量鼻骨侧位X射线摄影中的应用

目的探寻在鼻骨侧位X射线摄影中利用数字化X射线摄影(DR)组织均衡技术获取满足诊断需要的图像并降低患者辐射剂量的研究。方法利用人体模型进行常规的鼻骨侧位摄影,然后固定千伏值,在原有的mAs值上分别降低0.4、0.8、1.2 mAs进行摄片,再将降低剂量的图像采用DR组织均衡技术进行处理,比较不同图像对于满足诊断的需要和患者所接受的辐射剂量。结果常规摄影技术得到的图像需反复调节不同的窗宽、窗位才能显示密度、厚度不同的鼻骨与软组织;降低0.4、0.8 mAs,虽然图像的空间分辨率降低,但是采用DR组织均衡技术可在同一幅图像上清晰显示鼻骨与邻近软组织结构,同时降低患者的辐射剂量;降低1.2 mAs,不但图像的空间分辨率降低,而且无法采用DR组织均衡技术使图像达到满足诊断需要。结论采用DR组织均衡技术不仅能将密度、厚度不同的鼻骨及邻近软组织在同一副图像上清晰显示,而且能够有效降低患者的辐射剂量。     

Nasal asymmetry changes during growth and development in 6- to 12-year-old children with repaired unilateral cleft lip and palate: A 3D computed tomography analysis

Repaired unilateral cleft lip and palate (UCLP) is often accompanied by the deformity and asymmetry of the nasal region. Three-dimensional analysis was performed to investigate the relationship between nasal soft- and hard-tissue asymmetries, as well as the changes in nasal asymmetry with age, among children with repaired UCLP (age: 6–12 years). Forty-seven patients were included in this study. Their computed tomography records were retrieved for analysis of the 3D asymmetry of 10 landmarks of the nasal soft and hard tissues. We observed that asymmetry was more severe in nasal hard tissues than in soft tissues, particularly in the sagittal dimension. Compared with patients aged 6–9 years old, patients aged 10 to 12 years old had significantly increased vertical asymmetry at the base of the alar groove (Gbase, p = 0.027) and the lateral point of the piriform aperture (LPA), (p < 0.001). The correlation between the LPA and the alar region was weak to moderate (r = 0.290 to 0.488). In conclusion, we found no evidence of growth and development in nasal hard-tissue asymmetry among 6- to 12-year-old children with repaired UCLP, except for the vertical dimension. Nasal soft tissue exhibited a more preferable symmetry than hard tissue, and this could be attributed to the compensatory growth of nasal soft tissue, particularly in the vertical and sagittal dimensions. The weak to moderate correlations between nasal soft-tissue asymmetry and hard-tissue asymmetry were observed in the three dimensions. Surgeons should consider these factors when repositioning the nasal alar and controlling the size of the nostrils.     

Relationship between nose morphology and craniofacial structures in luzhou adults北大核心

BACKGROUND: Orthodontic treatment can improve facial aesthetics by changing the position of nose and chin. Therefore, fully-understanding of the nasal morphology and craniomaxillofacial structure is critical for the design of orthodontic treatment, so as to avoid the postoperative facial incongruity. OBJECTIVE: To study the correlation of nose morphology index with sex, sagittal skeletal features and vertical skeletal features and its differences in adults of Luzhou, and to explore the relationship between nasal parameters and craniofacial parameters, thereby providing references for the diagnosis and design of orthodontics. METHODS: Totally 240 adult patients in the Department of Orthodontics, Hospital of Stomatology, Southwest Medical University between 2014 and 2016 were enrolled, and X-ray examination of the oral and maxillofacial region was performed to measure the 27 related indexes. RESULTS AND CONCLUSION: The results of the three-factor ANOVA showed that sex-related significant factors in certain nasal parameters included nasal length, nasal tip height, alarheight, hump, soft-tissue facial convexity, columella convexity, and nasal bone length (P < 0.05). The sagittal skeletal features significantly influenced four nasal parameters including hump, nasolabialangle, nasomentalangle, soft-tissue facial convexity (P < 0.05). The vertical skeletal features were found to be significant for nasal-bone length, soft-tissue facial convexity (P < 0.05). Sex was found to be a significant correlation in nasal morphology and nasal size and nasal protrusion of the male were larger than those of the female. Sagittal skeletal classification had obvious influence on certain nasal parameters, but there were no significant differences in the nasal size among skeletal patterns. Vertical skeletal classification had obvious influence on certain nasal parameters. To conclude, nasal length, prominence, and form are associated with height, length and anteroposterior/vertical position of the maxilla and mandible. © 2018, Journal of Clinical Rehabilitative Tissue Engineering Research. All rights reserved.     

Morphological interaction between the nasal septum and nasofacial skeleton during human ontogeny

The nasal septal cartilage is thought to be a key growth center that contributes to nasofacial skeletal development. Despite the developmental influence of the nasal septum however, humans often exhibit a high frequency of septal deviation suggesting discordance in the growth between the septum and surrounding nasofacial skeleton. While there are numerous etiological factors that contribute to septal deviation, the surrounding nasofacial skeleton may also act to constrain the septum, resulting in altered patterns of growth. That is, while the nasal septum has a direct morphogenetic influence on aspects of the nasofacial skeleton, other nasofacial skeletal components may restrict septal growth resulting in deviation. Detailing the developmental relationship between these structures is important not only for understanding the causal determinants of nasal septal deviation, but also for developing a broader understanding of the complex interaction between the facial skeleton and chondrocranium. We selected 66 non‐syndromic subjects from the University of Minnesota Orthodontic Clinic who ranged from 7 to 18 years in age and had an existing pretreatment cone‐beam computed tomography (CBCT) scan. Using CBCT data, we examined the developmental relationship between nasal septal deviation and the surrounding nasofacial skeleton. We measured septal deviation as a percentage of septal volume relative to a modeled non‐deviated septum. We then collected a series of coordinate landmark data in the region immediately surrounding the nasal septum in the midsagittal plane representing the nasofacial skeleton. First, we examined ontogenetic changes in the magnitude of nasal septal deviation relative to chronological age and nasofacial size. Next, using Procrustes‐based geometric morphometric techniques, we assessed the morphological relationship between nasal septal deviation and nasofacial skeletal shape. Our results indicate that variation in the magnitude of nasal septal deviation was established in our earliest age group and maintained throughout ontogeny. Moreover, nasal septal deviation was correlated with non‐allometric variation in nasofacial shape restricted to the region of the anterior sphenoid body. Ultimately, our results suggest that early developmental variation in midline basicranial components may act to alter or constrain patterns of nasal septal growth.     

Bilateral cleft lip and palate: A morphometric analysis of facial skeletal form using cone beam computed tomography

Bilateral cleft lip and palate (BCLP) is caused by a lack of merging of maxillary and nasal facial prominences during development and morphogenesis. BCLP is associated with congenital defects of the oronasal facial region that can impair ingestion, mastication, speech, and dentofacial development. Using cone beam computed tomography (CBCT) images, 7‐ to 18‐year old individuals born with BCLP (n = 15) and age‐ and sex‐matched controls (n = 15) were retrospectively assessed. Coordinate values of three‐dimensional facial skeletal anatomical landmarks (n = 32) were measured from each CBCT image. Data were evaluated using principal coordinates analysis (PCOORD) and Euclidean Distance Matrix Analysis (EDMA). PCOORD axes 1–3 explain approximately 45% of the morphological variation between samples, and specific patterns of morphological differences were associated with each axis. Approximately, 30% of facial skeletal measures significantly differ by confidence interval testing (α = 0.10) between samples. While significant form differences occur across the facial skeleton, strong patterns of differences are localized to the lateral and superioinferior aspects of the nasal aperture. In conclusion, the BCLP deformity significantly alters facial skeletal morphology of the midface and oronasal regions of the face, but morphological differences were also found in the upper facial skeleton and to a lesser extent, the lower facial skeleton. This pattern of strong differences in the oronasal region of the facial skeleton combined with differences across the rest of the facial complex underscores the idea that bones of the craniofacial skeleton are integrated. Clin. Anat. 28:584–592, 2015. © 2015 Wiley Periodicals, Inc.     

Localized vascular regression during limb morphogenesis in the chicken embryo. I. Spatial and temporal changes in the vascular pattern

Morphogenesis of the vertebrate limb bud depends upon reciprocal interactions between epithelial and mesenchymal tissues. A characteristic limb vascular pattern is essential for normal limb outgrowth. The vascular pattern in the distal portion of the wing bud was examined by ink injection and compared to the sites of cartilage differentiation, as indicated by [35S]-incorporation. During development, avascular areas arose in three distinct locations within the vascularized mesoderm. These areas corresponded to the distal skeletal elements, referred to as digits 2, 3, and 4. Incorporation of radioactive sulfate was high in the avascular areas and low in the adjacent vascular tissue. Examination of autoradiographs of ink-injected limbs suggested that the appearance of avascular regions preceded the accumulation of sulfated cartilage matrix. These results indicate that remodeling of the limb vasculature is related to the formation of the skeletal pattern.     

Diversity in primary palate ontogeny of amniotes revealed with 3D imaging

The amniote primary palate encompasses the upper lip and the nasal cavities. During embryonic development, the primary palate forms from the fusion of the maxillary, medial nasal and lateral nasal prominences. In mammals, as the primary palate fuses, the nasal and oral cavities become completely separated. Subsequently, the tissue demarcating the future internal nares (choanae) thins and becomes the bucconasal membrane, which eventually ruptures and allows for the essential connection of the oral and nasal cavities to form. In reptiles (including birds), the other major amniote group, primary palate ontogeny is poorly studied with respect to prominence fusion, especially the formation of a bucconasal membrane. Using 3D optical projection tomography, we found that the prominences that initiate primary palate formation are similar between mammals and crocodilians but distinct from turtles and lizards, which are in turn similar to each other. Chickens are distinct from all non-avian lineages and instead resemble human embryos in this aspect. The majority of reptiles maintain a communication between the oral and nasal cavities via the choanae during primary palate formation. However, crocodiles appear to have a transient separation between the oral and nasal cavities. Furthermore, the three lizard species examined here, exhibit temporary closure of their external nares via fusion of the lateral nasal prominences with the frontonasal mass, subsequently reopening them just before hatching. The mechanism of the persistent choanal opening was examined in chicken embryos. The mesenchyme posterior/dorsal to the choana had a significant decline in proliferation index, whereas the mesenchyme of the facial processes remained high. This differential proliferation allows the choana to form a channel between the oral and nasal cavities as the facial prominences grow and fuse around it. Our data show that primary palate ontogeny has been modified extensively to support the array of morphological diversity that has evolved among amniotes.     

Chondromyxoid fibroma of the femur: a case report with intra-cortical location.

Chondromyxoid fibroma (CMF) is the least common benign cartilaginous tumor, comprising less than 0.5 to 1% of all skeletal neoplasms. This subject was a 16-year-old female with a three-year history of pain involving the distal femoral metaphysis. This case showed an unusual feature: it was intracortical in location. Radiologic differential diagnosis included metaphyseal fibrous defect, periosteal chondroma, simple or aneurysmal bone cyst, and cortical abscess. On operation, the lesion filled the intracortical defect with whitish myxoid soft tissue, bulging into the adjacent soft tissue. Microscopically, it showed typical features of chondromyxoid fibroma composed of mainly myxoid nodules and peripheral fibrous elements with focal chondroid differentiation.     

Skeletal morphology and development of the olfactory region of Spea (Anura: Scaphiopodidae)

The nasal capsules of anurans are formed by an intricate set of sac-like cavities that house the olfactory organ and constitute the beginning of the respiratory system. In tadpoles, nasal capsules do not have a respiratory function, but each is composed of a single soft tissue cavity lined with olfactory epithelium. Our study has revealed that in Spea the nasal cartilages and septomaxillae are de novo adult structures that form dorsal to the larval skeleton of the ethmoid region. The only element of the adult nasal capsule that is partially derived from the larval skeleton is the solum nasi. Development of the nasal skeleton begins at about Gosner Stage 31, with chondrification of the septum nasi and lamina orbitonasalis. The alary cartilage and superior prenasal cartilage are the first of the anterior nasal cartilages to chondrify at Gosner Stage 37. By Gosner Stages 40/41, the ethmoid region is composed of the larval structures ventrally and the adult structures dorsally. By Stage 44, the larval structures have eroded. The adult nasal capsule is characterized by: (1) a septum nasi that projects ventrally beyond the plane of the nasal floor; (2) a paranasal commissure that forms the ventral margin of the fenestra nasolateralis; and (3) a large skeletal support for the eminentia olfactoria formed by the nasal floor and vomer. The timing of chondrification of the anterior nasal cartilages and the development of the postnasal wall, inferior prenasal cartilage, fenestra nasolateralis, and paranasal commissure are discussed and compared with those of other anuran species. This study also includes a discussion of the morphology of the skeletal support for the eminentia olfactoria, a structure best developed in distinctly ground-dwelling frogs such as spadefoot toads. Finally, we propose a more precise restriction of the terminology that is used to designate the posterior structures of the olfactory region of anurans.     

Improved Rubin–Bodner model for the prediction of soft tissue deformations

In craniomaxillofacial (CMF) surgery, a reliable way of simulating the soft tissue deformation resulted from skeletal reconstruction is vitally important for preventing the risks of facial distortion postoperatively. However, it is difficult to simulate the soft tissue behaviors affected by different types of CMF surgery. This study presents an integrated bio-mechanical and statistical learning model to improve accuracy and reliability of predictions on soft facial tissue behavior. The Rubin–Bodner (RB) model is initially used to describe the biomechanical behavior of the soft facial tissue. Subsequently, a finite element model (FEM) computers the stress of each node in soft facial tissue mesh data resulted from bone displacement. Next, the Generalized Regression Neural Network (GRNN) method is implemented to obtain the relationship between the facial soft tissue deformation and the stress distribution corresponding to different CMF surgical types and to improve evaluation of elastic parameters included in the RB model. Therefore, the soft facial tissue deformation can be predicted by biomechanical properties and statistical model. Leave-one-out cross-validation is used on eleven patients. As a result, the average prediction error of our model (0.7035 mm) is lower than those resulting from other approaches. It also demonstrates that the more accurate bio-mechanical information the model has, the better prediction performance it could achieve.     

Nasal septal and craniofacial form in European- and African-derived populations

As a component of the chondrocranium, the nasal septum influences the anteroposterior dimensions of the facial skeleton. The role of the septum as a facial growth center, however, has been studied primarily in long-snouted mammals, and its precise influence on human facial growth is not as well understood. Whereas the nasal septum may be important in the anterior growth of the human facial skeleton early in ontogeny, the high incidence of nasal septal deviation in humans suggests the septum's influence on human facial length is limited to the early phases of facial growth. Nevertheless, the nasal septum follows a growth trajectory similar to the facial skeleton and, as such, its prolonged period of growth may influence other aspects of facial development. Using computed tomography scans of living human subjects (n = 70), the goal of the present study is to assess the morphological relationship between the nasal septum and facial skeleton in European- and African-derived populations, which have been shown to exhibit early developmental differences in the nasal septal-premaxillary complex. First we assessed whether there is population variation in the size of the nasal septum in European- and African-derived samples. This included an evaluation of septal deviation and the spatial constraints that influence variation in this condition. Next, we assessed the relationship between nasal septal size and craniofacial shape using multivariate regression techniques. Our results indicate that there is significant population variation in septal size and magnitude of septal deviation, both of which are greater in the European-derived sample. While septal deviation suggests a disjunction between the nasal septum and other components of the facial skeleton, we nevertheless found a significant relationship between the size of the nasal septum and craniofacial shape, which appears to largely be a response to the need to accommodate variation in nasal septal size.     

Sucker with a fat lip: The soft tissues underlying the viscoelastic grip of remora adhesion

Remoras are fishes that attach to a broad range of hosts using an adhesive disc on their head that is derived from dorsal fin elements. Research on the adhesive mechanism of remoras has focused primarily on the skeletal components of the disc and their contribution to generating suction and friction. However, the soft tissues of the disc, such as the soft lip surrounding the bony disc and the muscles that control the bony lamellae, have been largely ignored. To understand the sealing mechanism of the disc, it is imperative to understand the tissue morphology and material properties of the soft lip. Here, we show that the soft lip surrounding the remora disc is comprised of discrete multilayered collagen, fat, and elastic tissues which we hypothesize to have specific roles in the viscoelastic sealing mechanism of the remora disc. The central, heavily vascularized fat and collagen layer are infiltrated by strands of elastic tissue and surrounded by crossed-fiber collagen. A newly described jubilee muscle underneath the adhesive disc provides a mechanism for stopping venous return from the disc lip, thereby allowing it to become engorged and create a pressurized fit to the attachment substrate. Thus, the remora lip acts as a vascular hydrostat.