Utility of a modified vascular corrosion casting technique in the diagnosis of fetal total anomalous pulmonary venous connection.

Total anomalous pulmonary venous connection (TAPVC) is a rare congenital cardiac malformation, and prenatal detection of TAPVC malformation remains a challenging. TAPVC can be easily missed or misdiagnosed in prenatal examinations. This study was aimed to use the modified vascular corrosion casting technique to prepare fetal cardiovascular casts with TAPVC and investigate the utility of cardiovascular casting for the demonstration of fetal TAPVC. The retrospective study enrolled twenty fetuses (22 to 29 + 4 gestational weeks) with TAPVC diagnosed by prenatal echocardiography and casting technique from May 2015 to May 2020. Pre- and postnatal medical records, including results obtained by prenatal ultrasound, postpartum computed tomography angiography, as well as anatomic and cardiovascular casting findings were carefully reviewed and analyzed. In twenty cases, 80% (16/20) had intra- or extracardiac malformations. The TAPVC types were supracardiac (n = 8), cardiac (n = 6), infracardiac (n = 4), and mixed (n = 2). The diagnosis of 1 case each of supracardiac and cardiac TAPVC was modified to partial anomalous pulmonary venous connection; additionally, 4 malformations were missed and 2 were misdiagnosed, including an anomalous left brachiocephalic vein in supracardiac TAPVC, abnormal inflow of the hepatic vein and a double inferior vena cava in infracardiac TAPVC; and bilateral ductus arteriosus in infracardiac TAPVC; a tetralogy of Fallot in cardiac TAPVC that was corrected to right ventricular double outlet; and an absence of ductus arteriosus that was misdiagnosed as slim ductus arteriosus. Comparing with ultrasound, casting technique has its own superiority in exhibiting TAPVC abnormalities, especially in certain types such as course, origin and absence abnormalities of ductus. Postpartum cardiovascular casts can accurately depict the branch structure of the heart's larger vessels, and may be used as a clinical assessment and teaching method in complex cardiac malformations.

On the characterization of functionally graded biomaterial primed through a novel plaster mold casting process.

The current work presents a novel plaster mold casting (PMC) process for fabricating functionally graded biodegradable materials (FGBMs) for orthopedics applications. According to the proposed route, the plaster molds were first prepared by using a hybrid and variable mixture of Plaster of Paris (PoP) and hydroxyapatite (HAP). Upon drying, molten magnesium (Mg) alloy was poured in the mold cavity and allowed to solidify. Various experiments have been conducted as per Taguchi based design of experimentation to study the effect of PoPX/HAP proportion, mixing time, and baking times on mechanical, corrosion, and cytocompatibility performances of the resulting FGBM. It has been revealed by the scanning electron microscopy (SEM) that uniform layers of HAP particles were developed on the prepared specimens, revealed the novelty of the route. The mechanical properties, in case of surface hardness and impact strength, the optimum results were obtained with PoP(x = 90% by wt.) and HAP(y = 10% by wt.). Further, the corrosion investigations highlighted that the sample prepared with PoP(x = 70% by wt.) and HAP(y = 30% by wt.) proportion possessed excellent corrosion resistance. Moreover, the cytocompatibility analysis revealed that all the developed FGBM are substantially bioactive and promoted cell adhesion, proliferation, differentiation, and various other cytoplasmic activities. However, in this case, FGBM with PoP(x = 70% by wt.) and HAP(y = 30% by wt.) proportion was found superior. The overall results of the present work supported the developed FGBM components and involved the PMC route as a potential candidate for various orthopedics fabrications.

Corrosion casting of the temporal bone: Review of the technique.

The temporal bone has the most sophisticated anatomy of the whole skeleton. Its study is a challenge for students and surgeons. An inverse model of the visually obscured cavities and canals can facilitate better three-dimensional orientation and investigation. This can be made by means of corrosion casting, which is an established technique first documented on the temporal bone at the beginning of the nineteenth century. The prepared specimens are suitable not only for teaching purposes but also for research on the fascinating topography of the osseous labyrinth and the whole temporal bone. Many important studies on temporal bone anatomy are based on this technique. An extensive review of the pertinent literature is provided in relation to each method available.

Methodology of preparation of corrosive specimens from human placenta - A technical note.

Detailed knowledge of the anatomy of human placenta vessels is clinically essential and requires the use of many different anatomical and histological techniques. One of the interesting methods of visualising vessels is the corrosion technique. It enables spatial visualisation of the vascular network of the analysed organ. The authors present a developed, own method of preparing the corrosive preparations from human placenta. They underline the advantages and disadvantages of this technique. They describe solutions aimed at reducing the costs of the process. They show that corrosion technology enables relatively fast and inexpensive visualisation of arterial and venous vessels of the human placenta.

Corrosion casting in anatomy: Visualizing the architecture of hollow structures and surface details.

Corrosion casting is the technique by which a solid, negative replica is created from a hollow anatomical structure and liberated from its surrounding tissues. For centuries, different types of hardening substances have been developed to create such casts, but nowadays, thermosetting polymers are mostly used as casting medium. Although the principle and initial set-up are relatively easy, producing high-quality casts that serve their intended purpose can be quite challenging. This paper evaluates some of the more popular casting resins that are currently available and provides a step-by-step overview of the corrosion casting procedure, including surface casts of anatomical structures. Hurdles and pitfalls are discussed, along with possible solutions to circumvent them, based on personal experience by the authors.

Corrosion casting, a known technique for the study and teaching of vascular and duct structure in anatomy / Inyección corrosión, una técnica conocida para el estudio y enseñanza de ductos y estructuras vasculares en anatomía

Teaching and learning anatomy, as a process, has changed. Fresh cadavers were once used as a tool for the student to approach the human body in order to overcome theoretical knowledge and gain applied expertise. Today, techniques such as corrosion casting are known to be a more effective way of achieving optimal results with the students. This paper examines a method to apply this technique to an organ using different polymers. The concentrations for acrylic, epoxy resin, polyester resin, and room temperature vulcanization (RTV) silicone are described, as well as the corresponding diameter of the duct to be injected with each one. A variety of specimens obtained using this technique, their qualities and characteristics are presented. The results of using these procedures while involving the students, showed increased sense of responsibility, dedication and awareness, which led them to take the class more seriously and enjoy the process of learning. Additionally, the specimens left by the students will help future classes reduce the number of specimens needed.

El proceso de aprendizaje y enseñanza en anatomía ha cambiado recientemente, el cadáver fue la primera herramienta que permitía al estudiante una aproximación practica al cuerpo humano, facilitando que este se sobrepusiera al conocimiento teórico adquirido en el aula, y desarrollara experticia aplicada. Hoy en día, técnicas como la inyección corrosión son conocidas por lograr mejores resultados con los estudiantes. Este trabajo presenta un método para aplicar esta técnica a un órgano, mediante el uso de diferentes polímeros. Las concentraciones adecuadas de acrílico, resina epoxica, resina poliéster, y silicona RTV (room temperature vulcanization) son descritas, así como el diámetro sugerido para el uso de cada polímero. Se presenta una variedad de especímenes obtenidos mediante esta técnica, así como sus cualidades y características. Al integrar a los estudiantes en el proceso de creación de los especímenes, estos demuestran mayor sentido de responsabilidad, dedicación y autoconciencia, generando mayor compromiso, y entusiasmo con la clase y el proceso de aprendizaje. Adicionalmente, los especímenes producidos por ellos, serán de gran utilidad para clases a futuro.

The use of porcine corrosion casts for teaching human anatomy.

In teaching and learning human anatomy, anatomical autopsy and prosected specimens have always been indispensable. However, alternative methods must often be used to demonstrate particularly delicate structures. Corrosion casting of porcine organs with Biodur E20® Plus is valuable for teaching and learning both gross anatomy and, uniquely, the micromorphology of cardiovascular, respiratory, digestive, and urogenital systems. Assessments of casts with a stereomicroscope and/or scanning electron microscope as well as highlighting cast structures using color coding help students to better understand how the structures that they have observed as two-dimensional images actually exist in three dimensions, and students found using the casts to be highly effective in their learning. Reconstructions of cast hollow structures from (micro-)computed tomography scans and videos facilitate detailed analyses of branching patterns and spatial arrangements in cast structures, aid in the understanding of clinically relevant structures and provide innovative visual aids. The casting protocol and teaching manual we offer can be adjusted to different technical capabilities and might also be found useful for veterinary or other biological science classes.

Orbital venous pattern in relation to extraorbital venous drainage and superficial lymphatic vessels in rats.

The purpose of this study was to demonstrate the normal and variant anatomy of extraorbital and intraorbital venous drainage together with retroorbital communication, and determine the lymphatic drainage from the superficial orbital region with a potential outlet of lymphatic vessel into the venous bloodstream. The study of the venous system was carried out on 32 Wistar rats by using corrosion casts methods and radiography, while the lymphatic system was studied in 12 Wistar rats following ink injection. Superficially, orbital veins are connected with extraorbital veins running through angular vein of the eye and the superficial temporal vein, and via the pterygoid plexus with the maxillary vein, which provide readily accessible communication routes in the spread of infection. The extent of intraorbital and periorbital venous drainage was ensured by the dorsal and ventral external ophthalmic vein through the infraorbital vein, which together formed the principal part of the ophthalmic plexus. Venous drainage of the eyeball was carried out mainly by the vortex veins, ciliary veins and internal ophthalmic vein. The highest variability, first presented by differences in structural arrangement and formation of anastomoses, was observed within the ventral external ophthalmic vein (22 cases) and the medial vortex vein (10 cases). Four vortex veins, one vein in each quadrant of the eye, were observed in rats. The vortex vein located on the ventral side of the eyeball was occasionally found as two veins (in four cases) in the present study. The lymphatic vessel from the lower eyelid entered into the mandibular lymph centre, and from the upper eyelid entered into the superficial cervical lymph centre, but both drained into the deep cranial cervical lymph node. The direct entry of lymph entering the veins without passing through lymph nodes was not observed.

A multilevel framework to reconstruct anatomical 3D models of the hepatic vasculature in rat livers.

The intricate (micro)vascular architecture of the liver has not yet been fully unravelled. Although current models are often idealized simplifications of the complex anatomical reality, correct morphological information is instrumental for scientific and clinical purposes. Previously, both vascular corrosion casting (VCC) and immunohistochemistry (IHC) have been separately used to study the hepatic vasculature. Nevertheless, these techniques still face a number of challenges such as dual casting in VCC and limited imaging depths for IHC. We have optimized both techniques and combined their complementary strengths to develop a framework for multilevel reconstruction of the hepatic circulation in the rat. The VCC and micro-CT scanning protocol was improved by enabling dual casting, optimizing the contrast agent concentration, and adjusting the viscosity of the resin (PU4ii). IHC was improved with an optimized clearing technique (CUBIC) that extended the imaging depth for confocal microscopy more than five-fold. Using in-house developed software (DeLiver), the vascular network - in both VCC and IHC datasets - was automatically segmented and/or morphologically analysed. Our methodological framework allows 3D reconstruction and quantification of the hepatic circulation, ranging from the major blood vessels down to the intertwined and interconnected sinusoids. We believe that the presented framework will have value beyond studies of the liver, and will facilitate a better understanding of various parenchymal organs in general, in physiological and pathological circumstances.

Microcirculation alterations in experimentally induced gingivitis in dogs.

The present study aimed to morphologically examine the gingival microvascular network using a microvascular resin cast (MRC) technique, and to investigate how inflammatory disease functionally affects gingival microcirculation using laser Doppler flowmetry (LDF). We used four beagle dogs with healthy periodontal tissue as experimental animals. To cause periodontal inflammation, dental floss was placed around the cervical neck portions of the right premolars. The unmanipulated left premolars served as controls, and received plaque control every 7 days. After 90 days, gingivitis was induced in the experimental side, while the control side maintained healthy gingiva. To perform morphological examinations, we used an MRC method involving the injection of low-viscosity synthetic resin into the blood vessels, leading to peripheral soft-tissue dissolution and permitting observation of the bone, teeth, and vascular cast. Gingival blood flow was estimated using an LDF meter. The control gingival vasculature showed hairpin-loop-like networks along the tooth surface. The blood vessels had diameters of 20-40 µm and were regularly arranged around the cervical portion. On the other hand, the vasculature in the experimental group was twisted and gathered into spiral forms, with blood vessels that had uneven surfaces and smaller diameters of 8-10 µm. LDF revealed reduced gingival blood flow in the group with experimentally induced gingivitis compared to controls. The actual measurements of gingival blood flow by LDF were in agreement with the alterations that would be expected based on the gingivitis-induced morphological alterations observed with the MRC technique.

The Vascular Microarchitecture of the Human Fetal Pancreas: A Corrosion Casting and Scanning Electron Microscopy Study.

OBJECTIVES: Detailed knowledge on the development of the pancreas is required to understand the variability in its blood supply. The aim of our study was to use the corrosion casting method combined with scanning electron microscopy to study the organization of the pancreatic microcirculation in human fetuses. METHODS: The study was conducted on 28 human fetuses aged 18 to 25 gestational weeks. The fetal vasculature was appropriately prepared and then perfused with a low-viscosity Mercox CL-2R resin. The prepared vascular casts of the surface of the fetal pancreas were then examined in scanning electron microscopy and digitally analyzed. RESULTS: The lobular structure of the pancreas has a strong impact on the organization of the microvasculature. The lobular networks were supplied by the interlobular arteries and drained by the interlobular veins. The vascular system of fetal human pancreas has many portal connections, including islet-lobule and islet-duct portal circulations, which likely play a key role in the coordination of both endocrine and exocrine pancreatic functions. CONCLUSIONS: The organization of the microvascular network of the human pancreas in fetuses aged 18 to 25 gestational weeks is very similar to that of an adult but with more prominent features suggesting active processes of angiogenesis and vascular remodeling.

Microvascularization of the spleen in larval and adult Xenopus laevis: Histomorphology and scanning electron microscopy of vascular corrosion casts.

Microvascular anatomy and histomorphology of larval and adult spleens of the Clawed Toad, Xenopus laevis were studied by light microscopy of paraplast embedded serial tissue sections and scanning electron microscopy (SEM) of vascular corrosion casts (VCCs). Histology showed i) that white and red pulp are present at the onset of metamorphic climax (stage 57) and ii) that splenic vessels penetrated deeply into the splenic parenchyma at the height of metamorphic climax (stage 64). Scanning electron microscopy of VCCs demonstrated gross arterial supply and venous drainage, splenic microvascular patterns as well as the structure of the interstitial (extravasal) spaces representing the "open circulation routes." These spaces identified themselves as interconnected resin masses of two distinct forms, namely "broccoli-shaped" forms and highly interconnected small resin structures. Arterial and venous trees were clearly identified, as were transitions from capillaries to interstitial spaces and from interstitial spaces to pulp venules. Venous sinuses were not diagnosed (nonsinusal spleen). The splenic circulation in Xenopus laevis is "open." It is hypothesized that red blood cells circulate via splenic artery, central arteries, penicillar arteries, and red pulp capillaries primarily via "broccoli-shaped" interstitial spaces, pulp venules and veins into subcapsular veins to splenic veins while lymphocytes circulate also via the interstitial spaces represented by the highly interconnected small resin structures in vascular corrosion casts. In physiological terms, the former most likely represent the fast route for blood circulation, while the latter represent the slow route. J. Morphol. 277:1559-1569, 2016. © 2016 Wiley Periodicals, Inc.

Cardiovascular cast model fabrication and casting effectiveness evaluation in fetus with severe congenital heart disease or normal heart.

To investigate the application and effectiveness of vascular corrosion technique in preparing fetal cardiovascular cast models, 10 normal fetal heart specimens with other congenital disease (control group) and 18 specimens with severe congenital heart disease (case group) from induced abortions were enrolled in this study from March 2013 to June 2015 in our hospital. Cast models were prepared by injecting casting material into vascular lumen to demonstrate real geometries of fetal cardiovascular system. Casting effectiveness was analyzed in terms of local anatomic structures and different anatomical levels (including overall level, atrioventricular and great vascular system, left-sided and right-sided heart), as well as different trimesters of pregnancy. In our study, all specimens were successfully casted. Casting effectiveness analysis of local anatomic structures showed a mean score from 1.90±1.45 to 3.60±0.52, without significant differences between case and control groups in most local anatomic structures except left ventricle, which had a higher score in control group (P=0.027). Inter-group comparison of casting effectiveness in different anatomical levels showed no significant differences between the two groups. Intra-group comparison also revealed undifferentiated casting effectiveness between atrioventricular and great vascular system, or left-sided and right-sided heart in corresponding group. Third-trimester group had a significantly higher perfusion score in great vascular system than second-trimester group (P=0.046), while the other anatomical levels displayed no such difference. Vascular corrosion technique can be successfully used in fabrication of fetal cardiovascular cast model. It is also a reliable method to demonstrate three-dimensional anatomy of severe congenital heart disease and normal heart in fetus.

Degeneration of stria vascularis in age-related hearing loss; a corrosion cast study in a mouse model.

Conclusion With age, in a mouse model, degenerative changes to the capillaries of the stria vascularis are observed. These range from a narrowing of vessel lumen to complete degeneration of strial vessels. Other vascular beds in the cochlea are relatively unchanged with age. Strial capillaries at the cochlear base are significantly more affected than those in mid-apical turns. Objectives Previous work suggests that age-related hearing loss is associated with degenerative changes to cochlear vasculature; the term strial presbyacusis is often cited. This study reports on vascular changes observed in a murine model of presbyacusis, analyzed using corrosion cast techniques. Methods A novel corrosion cast technique was developed to compare cochlear vasculature in control mice (non-presbycusic, CD1) and old (> 6 months) C57BL/6 animals. ABR measures indicated a significant age-related threshold elevation in the C57BL/6 mice. Cochlear vascular casts were imaged using scanning electron microscopy, and vessel degeneration was quantified by measuring capillary diameters. Results Corrosion casts of cochlear vasculature in 6-12 month old C57BL/6 mice reveal significant degeneration of stria vascularis. Other capillary beds (spiral ligament and the spiral limbus) appear unchanged. Comparison of strial capillary diameters reveals significantly more damage in basal/lower-turn regions compared with the cochlear mid-turn.

Fabrication of biomimetic vascular scaffolds for 3D tissue constructs using vascular corrosion casts.

Vascularization is among the most pressing technical challenges facing tissue engineering of 3D organs. While small engineered constructs can rely solely on vascular infiltration and diffusion from host tissues following implantation, larger avascular constructs do not survive long enough for vessel ingrowth to occur. To address this challenge, strategies for pre-vascularization of engineered constructs have been developed. Various biofabrication techniques have been utilized for pre-vascularization, but limitations exist with respect to the size and complexity of the resulting vessels. To this end, we developed a simple and novel fabrication method to create biomimetic microvascular scaffolds using vascular corrosion casting as a template for pre-vascularization of engineered tissue constructs. Gross and electron microscopic analysis demonstrates that polycaprolactone (PCL)-derived kidney vascular corrosion casts are able to capture the architecture of normal renal tissue and can serve as a sacrificial template for the creation of a collagen-based vascular scaffold. Histological analysis demonstrates that the collagen vascular scaffolds are biomimetic in structure and can be perfused, endothelialized, and embedded in hydrogel tissue constructs. Our scaffold creation method is simple, cost effective, and provides a biomimetic, tissue-specific option for pre-vascularization that is broadly applicable in tissue engineering. STATEMENT OF SIGNIFICANCE: Tissues in the body are vascularized to provide nutrients to the cells within the tissues and carry away waste, but creating tissue engineered constructs with functional vascular networks has been challenging. Current biofabrication techniques can incorporate blood vessel-like structures with straight or simple branching patterns into tissue constructs. Unfortunately, these techniques are expensive, complicated and create simplified versions of the complex vessel structures seen in native tissue. Our technique uses novel vascular corrosion casts of normal tissue as templates to create vascular scaffolds that are a copy of normal vessels. These vascular scaffolds can be easily incorporated into 3D tissue constructs. Our process is simple, inexpensive and inherently tissue-specific, making it widely applicable in the field of tissue engineering.

Morphology of the Canine Omentum Part 2: The Omental Bursa and its Compartments Materialized and Explored by a Novel Technique.

The canine omental bursa is a virtual cavity enclosed by the greater and lesser omentum. While previous representations of this bursa were always purely schematic, a novel casting technique was developed to depict the three-dimensional organization of the omental bursa more consistently. A self-expanding polyurethane-based foam was injected into the omental bursa through the omental foramen in six dogs. After curing and the subsequent maceration of the surrounded tissues, the obtained three-dimensional casts could clearly and in a reproducible way reveal the omental vestibule, its caudal recess and the three compartments of the splenic recess. The cast proved to be an invaluable study tool to identify the landmarks that define the enveloping omentum. In addition, the polyurethane material can easily be discerned on computed tomographic images. When the casting technique is preceded by vascular injections, the blood vessels that supply the omentum can be outlined as well.

Blood supply to the thoracolumbar spinal cord in the laboratory mouse using corrosion and dissection techniques.

Mice are used frequently as experimental models in the study of ischemic spinal cord injury. The aim of the present study was to describe the arterial blood supply to the thoracolumbar spinal cord in the mouse. The study was carried out on 20 adult mice using the corrosion and dissection technique. Dorsal intercostal arteries were found as branches of the thoracic aorta: as 7 pairs in 80% of cases, as 8 pairs in 15% of cases and as 9 pairs in 5% of cases. The paired lumbar arteries arising from the abdominal aorta were present as 5 pairs in all cases. Along the entire thoracic and lumbar spinal regions, we observed left-sided branches entering the ventral spinal artery in 64.2% and right-sided branches in 35.8% of cases. Along the entire thoracic and lumbar spinal regions, the branches entering the dorsal spinal arteries were left-sided in 60.8% of cases and right-sided in 39.2% of cases. We found some variations in the site of origin of the artery of Adamkiewicz and in the number of dorsal spinal arteries. Documenting the anatomical variations in spinal cord blood supply in the laboratory mouse will aid the planning of future experimental studies and in determining the clinical relevance of such studies.

Partial corrosion casting to assess cochlear vasculature in mouse models of presbycusis and CMV infection.

Some forms of sensorineural hearing loss involve damage or degenerative changes to the stria vascularis and/or other vascular structures in the cochlea. In animal models, many methods for anatomical assessment of cochlear vasculature exist, each with advantages and limitations. One methodology, corrosion casting, has proved useful in some species, however in the mouse model this technique is difficult to achieve because digestion of non vascular tissue results in collapse of the delicate cast specimen. We have developed a partial corrosion cast method that allows visualization of vasculature along much of the cochlear length but maintains some structural integrity of the specimen. We provide a detailed step-by-step description of this novel technique. We give some illustrative examples of the use of the method in mouse models of presbycusis and cytomegalovirus (CMV) infection.

Vascular casting for the study of vascular morphogenesis.

Microvascularity and angiogenesis play a pivotal role during normal growth and in a variety of pathological conditions such as inflammation, tumor growth, macular degeneration, and tissue regeneration. Vascular corrosion casting has been established as a method to analyze and evaluate two- and three-dimensionally the morphology and architecture of blood vessels of organs and tissues, such as tumors, brains, embryos, or the chorioallantoic membrane. Microvascular casts may be further dissected for visualizing and quantifying vascular morphology using scanning electron microscopy (SEM), micro computed tomographic (µCT) imaging, or synchrotron radiation-based micro computed tomographic (SRµCT) imaging.