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Novice plastinators may assume that dissection of a specimen must be completed prior to commencement of the plastination process. However, further dissection is possible both during and after plastination which often results in enhancement of features chosen for display. The purpose of this presentation is to provide a range of examples of dissection techniques of plastinated material at various stages of the process. The importance of dissection prior to plastination is paramount because the final appearance of the specimen is dependent on the time, effort and technical expertise of the dissector. All extraneous connective tissue must be carefully removed by the prosector. Underwater dissection magnifies the connective tissue which can then be carefully removed to produce a smoother surface with muscle fascicles enhanced. Stents can be used to maintain the shape and size of vessel lumen and orifices. Other devices are used to maintain the correct relationships between structures during the process. Some of these devices can be retained while others are removed during the plastination process. Use of compressed air during the plastination process produces organs with a realistic size and shape, such as the lungs, stomach and intestines. Sections of organs can be produced after plastination from complete organs. As an example, brain slices can be produced from whole brains, often producing slices of better quality than the alternative of slicing the brain prior to plastination. In terms of presentation of plastinated specimens, there is definite benefit in using a range of techniques to highlight specified features and to maintain the correct appearance of structures that tend to collapse during the plastination process.

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As sophisticated diagnostic imaging technology has become commonplace in the clinical environment, it has never been more imperative for the medical student, clinician and researcher alike to understand and further explore the cross sectional approach to the human body. Sheet plastination has proven to be a vital tool in the enhancement and clarification of anatomical concepts and relationships previously often difficult to appreciate. Sheet plastination is a means in which thin slices of organs, extremities, brain or even whole in situ sections may be specially processed and encapsulated within a clear, smooth resin sheet. Sections may vary in thickness from 2mm to 6mm depending upon the region, type of tissue and the desired result. Specimens are cut, dehydrated and vacuum impregnated with a polymer of either epoxy or polyester base and are subsequently processed between two glass plates using either heat or ultra violet light. The finished specimens offer excellent clarity, providing a vantage point to the submacroscopic level easily observed with the naked eye. Sections may also be further magnified using either a light microscope or CCD closed circuit video system. When viewing extremely fine vascular or nervous detail under a close-up video system, whole body sections may be viewed first in their entirety, then magnified at various levels to display anatomical relationships without the need for the interconnected tissues to become physically separated. Sheet plastination maintains the entire anatomical plane in a complete and uninterrupted state, thus retaining the overall structural integrity. Brain sections are greatly enhanced by a superb differentiation of the white and the gray matter. By closely observing a number of key plastination protocols, the individual serial sections display an exceptionally vivid degree of anatomical detail not previously visible in traditional cross sections, wet gross specimens or even, in some cases, radiographic images. Sheet plastinated specimens are an ideal link between three disciplines; namely cross-sectional anatomy, radiology and microscopy from just the one specimen.

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The "New Plastination Index" has been online since one year and is continuously growing. The author will review and explain the various sections of the index. Participants will also be invited to comment on their perception of the utility of the index and to suggest additions or modifications to it in order to make it as useful as possible for every person involved in plastination. The address is : www.uqtr.ca/plastination.

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The plastination technique offers a unique advantage over all the other techniques as it permits the display of internal organs that are dry and close to the living state. These organs can be placed into skeletons to enhance their value. Internal organs from a dog were plastinated according to the standard S10 technique. The skeleton of the dog was also cleaned and mounted. The plastinated organs were afterward positioned within the skeleton. This type of presentation allows people to see the size, shape and exact location of all the organs within the body. They can also enhance the interest for the various skeletons displayed in museums. We believe that this new kind of exhibit is worthy of interest for museums as well as pedagogical purposes.

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Impregnation is the exchange of a volatile intermediary solvent [acetone or methylene chloride (dichloromethane)] for a curable polymer and is the key point in the plastination process. Impregnation in the classic S10 procedure is carried out over several weeks. Dehydrated, solvent-saturated specimens are submerged in a polymer reaction-mixture inside the vacuum chamber. This reaction-mixture is made by mixing silicone polymer (S10) and the catalyst/chain extender (S3) at a ratio of 100:1. Submerged specimens are allowed to equilibrate with the reaction-mixture for a day. The next day pressure is decreased two-thirds of an atmosphere by closing the port and needle valves and starting the vacuum pump. When pressure has decreased two-thirds of an atmosphere (25cm Hg, 10 inches Hg), pressure is stabilized by opening the valve(s) slowly until pressure remains at this level. Small air bubbles that were mixed into the reaction mixture will rise to the polymer surface while pressure is lowered. The next day, the needle valve is closed a portion of a turn to decrease pressure 5cm Hg (2 in.). The pressure reading will be around 20cm Hg (9 in.). Each day pressure is decreased 2.5cm Hg (1 in.) and allowed to stabilize overnight. When pressure is near 8cm Hg (3 in.), bubbles will likely be seen rising to the surface and bursting continually. These bubbles are from acetone vaporizing and being pumped off. At this vacuum level, when bubbles are forming and rising to the top, do not decrease pressure. When no bubbles are rising, decrease pressure 1cm to enhance bubble formation (acetone vaporization). Vacuum is continued until near zero pressure is maintained for a few days and bubbles are very large or diminished in formation. End point time depends on volume of specimens and pump speed. When impregnation is complete, the vacuum pump is turned off and the plastination kettle with the specimens is allowed to return to ambience. After a few hours or days, the specimens are drained of excess polymer and brought to room temperature to allow the conclusion of draining of excess polymer. After the excess polymer has been drained from the specimens, specimen surfaces are wiped or blotted dry. The next and final step is curing. Curing (polymerization, hardening) is the process which changes the liquid polymer reaction-mixture into a solid. Two variations of curing may be used, slow cure and fast cure. Slow cure allows the chain extender of the polymer reaction-mixture time to create longer silicone molecules which will likely create a more flexible specimen. The catalyst has prepared the silicone polymer molecules to react with the chain extender and cross-linker. The specimen is placed on absorbent toweling, wiped of excess or oozing polymer and left at room temperature and environment for weeks to months. During this phase, hollow organs must be distended with air or absorbent material, as well as, all specimens must be molded into their best anatomical form. Fast cure uses daily applications of the cross-linker (S6) in a closed environment to begin the cross-linking of the silicone polymer molecules. This transforms the polymer from a liquid into a solid. During this time it is important to wipe excess polymer and drips or runs from the surface and crevices of the specimen. As well, hollow organs must be dilated and all specimens must be molded into their final anatomical position. After the surface is dry, the specimen may be used but should be kept in a closed environment (bag) for several weeks to assure curing into the depths of the organ.

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Vacuum is the key mechanism for the plastination process. Vacuum is read and recorded two ways: 1) Absolute pressure (AP) or 2) Vacuum. What these readings represent, when measuring the pressure (vacuum) or changes in pressure, varies depending on the type of instrumentation. Commonly, changes are measured via a Hg column, gauge or manometer. A column of Hg or vacuum/pressure gauge yields a higher reading as absolute pressure is decreased and is referred to as gauge pressure. However, a manometer yields a lower number as AP decreases and is read as absolute pressure. The manometer utilizes the difference in two columns of Hg. The vacuum gauge or column of Hg uses atmospheric pressure as point zero while the manometer uses total vacuum as point zero. Hence, the readings are at opposite poles of the 760mm scale (atmospheric pressure at sea level). Because most manometers used in plastination laboratories utilize two columns of Hg whose difference in height is 20cm or less, only the lower 1/3 of atmospheric pressure (<25cm) may be measured. Hence, a vacuum gauge or Hg column is necessary to monitor changes in absolute pressure (vacuum) in the earlier stages of impregnation (first two-thirds atmosphere decrease). Pressure is read in milli/centimeters or inches of Hg. Torr is another unit used to measure pressure. One Torr equals 1/760 of an atmosphere. Why/how vacuum for plastination? During tissue processing for electron microscopy, polymer penetrates only 1-2mm. Plastination of large specimens needs penetration of several cm. Vacuum lowers the vapor pressure of the solvent so that the solvent can be regulated and extracted slowly over a period of time even at a lower temperature. This slow release of solvent from the cells allows time for the more viscous polymer to enter the cells, thus replacing the evaporating solvent. Two solvents fit these criteria: acetone and dichloromethane (methylene chloride). The saturated vapor pressure (similar to boiling point) of dichloromethane is higher than that of acetone; 32.5mm Hg vs. 14.8mm at-25°C and 78.0mm vs. 35.9mm at -10°C respectively. Hence, methylene chloride will vaporize at a higher AP and be extracted before acetone at any given temperature or pressure. This shows that the greatest extraction of acetone will not occur until near 3.5cm AP. When using deep vats of silicone for impregnation, remember; pressure is proportional to depth. This results in the pressure being greater at the bottom of the polymer than on the surface of the polymer. At -15°C, acetone will remain in a specimen which is submerged 15 to 20cm below the surface of the polymer longer than a specimen near the top. The gauge reads surface pressure. When contemplating construction or purchase of a plastination kettle, the force generated when absolute pressure is decreased one atmosphere is 15 pounds per square inch (6.45cm2). At total vacuum, the one foot (30cm) cube desiccator used for plastination has 2,160 pounds (lbs) of force on its walls while a 46cm x 76cm (18 in. by 30 in.) medium size plastination kettle has 8,000 lbs of force and a 50cm x l27cm (20 in. x 50 in.) vacuum chamber has 15,000 lbs per square inch (6.45cm2).

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Plastination is touted as one of the great teaching innovations of the 20th century. It has numerous qualities of which tissue preservation is of foremost importance. Many hope that plastinated specimens do not replace cadaver dissection. Prior to a major curricular revision seven years ago, plastinated specimens were used primarily to supplement information on areas which are difficult to dissect, and to understand with professionally prepared plastinated dissections that would enhance understanding of these topics. A library of a wide range of specimens, as well as novel preparations and finds, birth defects, exotic animal preparations and diseased specimens were routinely plastinated. Plastinated specimens were usually placed in the laboratory after a region or system had been dissected. Two reasons: 1. This might assure more thorough dissection. 2. These specimens would be used primarily as a review of previously dissected areas. This approach works particularly well if you use the student dissections as a major portion of their examination. Since curricular change reduced laboratory time, such that even preferred dissections had to be removed or limited, plastinated specimens were seen as a mechanism to help resolve this situation. One such project was preparation and plastination of the proximal limbs of the horse and cow. Fifteen thoracic and pelvic limb preparations were dissected and plastinated to emphasize important structures of the proximal limbs, as well as, serve as the connection between the trunk and the distal limb, Neuroanatomy is now taught primarily with prosected plastinated brains of various species. Plastinated specimens may be pinned and/or photographed and labeled to highlight salient landmarks and a key prepared for the pinned or marked structures as well as suggested items that the student should be able to identify. Plastinated specimens are available 24 hours a day for student use. Students are asked to handle the plastinated specimens with clean hands (not gloves) and not to place plastinated specimens on wet dissection tables. Specimens are used frequently by upper classmen and clinical faculty to review the anatomy of an area prior to treatment of a clinical case. Specimens are used for public relations as in tours as well as for clients to demonstrate the problematic area of their pet. Plastinated specimens are used as props for educational talks by faculty or students at area schools or civic organizations. Plastinated specimens are also building a library of exotic or unusual anatomy that serves to document anatomical information of various species, pathology and anomalies.

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Plastination is a method that offers an ideal visual presentation of anatomical structure. This technique is widely and extensively used in teaching and in researching purposes. Plastination allows production of anatomical specimens that appear lifelike in state without many noticeable changes. Shrinkage of tissue is one of the disadvantages to plastination. Many researchers deduce that the shrinkage of specimens occurs during the stages of dehydration and impregnation. However, there are sufficient studies which evaluate the influence of plastination on the shrinkage of the tissue during the plastination procedure. The aim of this study was to evaluate the value of shrinkage that occurs during dehydration and impregnation using the standard S10 technique for plastination. Thirty kidneys obtained from adult mixed breed Landrace farm pigs were plastinated accolding to the standard protocol described by Biodur™. The kidneys were removed between 130-150 days of age when the body weight ranged from 50-70kg. Before plastination, each kidney was labeled with a plastic ring with an identification number. The kidneys were quantitatively evaluated considering the following measurements: greatest longitudinal length (LL), cranial pole width (CRP), caudal pole width (CDP) and weight (W). The qualitative evaluation of these parameters was performed before and after dehydration and silicone impregnation using a digital caliper ruler and a digital balance with a precision of 0.01g. Statistical analysis of each parameter was performed by t-test for dependent samples. The kidney morphometric measurements before and after dehydration revealed the following means: longitudinal length (LL) 9.82cm before and 9.77cm after (p:0.49), cranial pole width (CRP) 5.09cm before and 5.08cm after (p:0.86), caudal pole width (CDP) 4.63cm before and 4.6lcm after (p:0.66) and the weight (W) 90.99g before and 84.01g after (p<0.00). The results showed that the dehydration process influences tissue shrinkage but with no significant differences (p>0.05) except for the weight where there was a significant decrease of kidney weight (p<0.05). The results obtained after silicone impregnation reveal the following means: length (LL) 9.45cm, cranial pole width (CRP ) 4.75cm, caudal pole width (CDP) 4.36cm and weight (W) 98.55g. Compared with measurements made of kidneys before and after dehydration, these results clearly indicate significant differences (p<0.05) in all parameters in the period of impregnation. During our research, the shrinkage of kidneys was apparent and a significant change was recorded in the stage of impregnation. The level of shrinkage that occurred suggests that the most precise macroscopic morphological investigations of anatomical specimens and structures should not be carried out on plastinated specimens. The specimens obtained provided an excellent tool for demonstration of kidney morphology and can be used as a teaching model because the kidneys displayed anatomical details suitable for morphological studies.

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Specially designed plastinated organs aid the teaching-learning process when training to learn minimally invasive surgical techniques. These specimens allow a real life training opportunity using endoscopic techniques and skills prior to using a living patient. These experimental models should be used for the basic steps of specialized training and learning programs of minimally invasive surgery procedures. The morphological and physical characteristics of plastinated specimens are excellent to study the topographic and clinical anatomy of the bronchio-alveolar tree. Fixation of fresh tissue specimens was by perfusion of 5% formaldehyde through the trachea with a peristaltic pump for 8 hours. Later, fixative was rinsed from the tissue via flowing tap water. Dehydration was achieved by tracheal perfusion of 90% acetone for 24h. A weekly change into a higher percent acetone was performed until an acetone percent of >99% was maintained. North Carolina Silicone polymer (Neat 285 or 295) was used first to fill the lungs and then for impregnation at room temperature. After impregnation, the specimens remained at room temperature dilated with circulating air for several months to allow excess polymer to drain. Once drainage appeared complete, specimens were placed in a curing chamber and super-catalyst was added to the environment until all weeping had ceased and the lung surface was dry. Plastinated cardiopulmonary blocks and isolated lungs of dogs were produced to practice: 1. Respiratory endoscopic exploration of the trachea and bronchi; 2. Diagnostic and therapeutic techniques (cytology, biopsy, tracheal and bronchio-alveolar suction, endoscopic placement of tracheal stents in the stenotic model and 3. Selective intubations (endotracheal tubes of Robert-Shaw and bronchial brockade Univent).

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Many researchers interested in morphology have known that plastination is a unique technique of tissue preservation producing durable, dry and handleable specimens. However, there were few attempts to produce plastinated specimens in Korea. For the first time in Korea. the Catholic Institute for Applied Anatomy succeeded in producing plastinated specimens using the silicone S10 standard technique in July, 2003. Since then, our institute has plastinated 80 specimens and introduced the results of these specimens and future plans to the International Society for Plastination. Of the 80 plastinated specimens, 60 specimens were obtained from human cadavers and 20 specimens from plants and animals. All specimens were plastinated using the S10 technique, (48 specimens were treated with Biodur™ S10 and the others were with silicone made in Korea). During these 2 years, our institute gained experience with the S10 technique using varying specimens such as digestive organs, hearts, brains, bone, muscle, regional material (hemisected head or shoulder region), fetuses, pathologic specimens, animals and plants. Many problems were encountered and we selected three major problems to be solved for better products. The control of hardness, the maintenance of morphologic characteristics and the minimization of color change. Presently, to solve these problems, all records about material characteristics, work history and quality of plastination are entered into a database. On the basis of this database, one may find the value of silicone viscosity, modified dehydration and curing method according to material characteristics. Also, our institute is preparing additional plastination methods using epoxy and polyester resin.

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Since the introduction of plastination about three decades ago, anatomical specimens preserved in silicone have been broadly used in medical schools as a valuable resource to gross anatomy education. At the University of Michigan Medical School, plastinated specimens have become an essential part of medical, undergraduate and dental anatomy education. The newly implemented, system-based, integrated medical curriculum necessitated the introduction of a different set of specimens that are more relevant to the new curricular approach. The aim has been to demonstrate systemic and essential concepts in anatomy in order to promote students' independent learning. In the undergraduate "Introduction to Human Anatomy" course, laboratory visits were introduced into the syllabus where pertinent plastinated specimens were displayed. During the visits, faculty using these specimens explained the anatomical and the clinical relevance of the related systems. In the dental anatomy sessions, there has been more reliance on the use of plastinated specimens that demonstrate essential and inaccessible areas in the head and neck region. Medical and undergraduate students participated in preparing these specimens. Innovative approaches to enhance the quality of plastinated specimens were implemented such as coloring neurovascular pathways and casting hollow viscera to facilitate learning. The validity of these specimens was regularly tested through surveys administered to students. Also, a pilot study was conducted whereby the performance of a test group of medical students, who reviewed anatomy using the new set of specimens, was compared to that of a control group using the traditional set of specimens. Results indicated an overall acceptance of the new specimens as a valuable resource for learning anatomy. The reliance on plastinated specimens in education is certainly on the rise. Efforts in producing more relevant specimens for that purpose are focused on the exposure and coloring of essential neurovascular pathways. The new approach in preparing specimens is planned for a wider application of plastination in the future to facilitate comprehension of anatomical knowledge and to assist faculty and students in the effective utilization of the time allocated to anatomy.

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Plastination was developed for teaching as well as for research. In 1977, at the department of Anatomy of Heidelberg University. Dr. von Hagens invented plastination as a groundbreaking technology for preserving anatomical specimens with reactive polymers. The processes were patented between 1978 and 1982. This method has proved to be the superior method for preservation of gross specimens. Vienna was the first place to introduce this new method in the late 70's. Presently, the method is applied in more than 250 institutes for Human Anatomy, Clinical Pathology, Biology and Zoology worldwide. The "International Society for Plastination" was founded in 1986. The first issue of the Journal of the International Society of Plastination appeared in 1987. Optical properties, opaque or transparent, and mechanical properties, smooth and flexible or hard, can be chosen by appropriate composition of plastination resins. Plastination allows for preservation of specimens with completely visible surfaces and high durability. Plastinated specimens are odorless, non-toxic and mechanically resistant to a high degree. Plastination is a procedure during which water and fat of gross specimen are replaced by a polymerizable resin. In the past years, the use of plastinated slices has become an interesting research tool. Thin plastinated slices are essential if the histology or morphometrical investigations are to be studied on plastinated slices or if 3D reconstruction is desired. Histological examination can be performed up to a magnification of 40X. The major advantage of this method is that the structures remain intact and the decalcifying of bony tissue is not necessary.

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The E12 method of plastination is usually used to create 2.5 - 5mm transparent slices. If thinner slices, 0.5 - 1.5mm, are desired it is necessary to use the thin-slice plastination method. Using this method, the specimen must be first plastinated as a block and then cut into thinner slices. The impregnation temperature is the key element to obtain a proper impregnation of the desired tissue block and contrary to all other plastination methods high temperature is used. The main goal of this paper is to describe the use of high temperature for processing 1mm epoxy plastinated slices. Only by using high temperature is the polymer thin enough to penetrate into the middle of the processed specimen. One male unfixed human cadaver ankle was used for this study. The distal third of a limb was cut and the foot positioned in a 90° dorsal flexion. A tissue block containing the ankle was cut starting 40mm distal to the tip of the lateral malleolus and finishing 50mm proximal. The tissue block was dehydrated, degreased and finally impregnated with arsine mixture E12/E6/E600. Using a band saw, Exact 310 CP, the E12 block was cut into 1mm slices. Once scanned, these images of the plastinated slices were loaded into WinSURF and traced from the monitor. Once all contours were traced, the reconstruction was rendered and visualized and the model was qualitatively checked for surface discontinuities. An E12 block was produced that was hard and transparent. Thin, <1mm slices produced from this block were transparent and hard with good optical qualities. The finished E12 slices provided anatomic detail to the microscopic level. Thin slices <1mm are essential if the histology is to be studied on plastinated slices or if 3D reconstruction is desired. These thin slices can only be cut from a solid E12 block. Therefore, knowledge of controlling temperature and percent of accelerator in the thin plastination method is essential. Histological examination can be performed up to a magnification of 40X. The major advantage of this method is that the structures remain intact and the decalciffing of bony tissue is not necessary

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Decay is a vital process in nature but an impediment to morphological studies, teaching, and research. This is particularly true for biological specimens that shrink considerably when exposed to normal atmospheric conditions. Therefore, it has always been a goal to find suitable preservation techniques, especially for anatomists. Plastination is a unique technique of tissue preservation developed by Dr. Gunther von Hagens in Heidelberg, Germany in 1978. In this process, water and lipids in biological tissues are replaced by curable polymers (silicone, epoxy, polyester) which are subsequently hardened, resulting in dry, odorless and durable specimens. The class of polymer used determines the optical (transparent or opaque) and mechanical (flexible or firm) properties of the impregnated specimen. Silicone is used for whole specimens and thick body and organ slices to obtain a natural look. Epoxy resins are used for thin, transparent body and organ slices. Polyester-copolymer is exclusively used for brain slices to gain an excellent distinction of gray and white matter. The technique consists of four main steps: fixation, dehydration, forced impregnation and hardening (curing). Fixation can be accomplished by most conventional fixatives. Dehydration is achieved mainly by acetone because acetone also serves as the intermediary solvent during impregnation. Forced impregnation is the central step in plastination. Vacuum forces the acetone out of and the polymer into the specimen. Hardening (curing): finally the impregnated specimen is hardened by exposing it to a gaseous hardener (silicone) or by UVA-light and heat (polyester, epoxy). Plastinated specimens are perfect for teaching, particularly for neuroanatomy. Silicone plastinated brains are useful because they can be grasped literally and they are almost everlasting. Polyester plastination of brain slices provides an excellent distinction of gray and white matter and thus a better orientation. Plastination is carried out in many institutions worldwide and has obtained great acceptance particularly because of the durability of the plastinated specimens, the possibility for direct comparison to CT- and MR-images and the high teaching value of plastinated specimens.
Silicone (S10) standard procedure:
The S10 technique is the standard technique in plastination. Specimen impregnation with Biodur™ S10 results in opaque, more or less flexible and natural looking specimens. The procedure consists of the four main steps of plastination in addition to specimen dissection and preparation. Fixation can be achieved by all usual fixatives as formaldehyde solution, Kayserling solution etc. Hollow organs must be dilated during fixation as well as during dehydration and gas curing. Dehydration removes the specimen fluid as well as some fat. In this step, tissue fluid is replaced with an organic solvent. Either alcohol or acetone may be used as a dehydrating agent for plastination. Acetone is used in most cases because acetone also serves as the intermediary solvent during the next step forced impregnation. To minimize specimen shrinkage, dehydration is done in cold (-15°C to -25°C) acetone. If the removal of fat is also desired, the dehydrated specimen must be kept in acetone at room temperature for some time (this however, must not be done with nervous tissue, particularly with brains). An acetone amount of 10 times the specimen weight is best for good results. Dehydration is finished when the water content of the specimen is less than 1%. Equipment needed for dehydration includes a deep freezer (explosion proof or motor and compressor removed and placed in a different room) and an acetonometer to measure the content of water. Forced impregnation is the central step of plastination. In this step, the intermediary solvent (acetone) is replaced with a curable polymer (Biodur™ S10). The silicone polymer S10 is mixed with a curing agent Biodur™ S3 (1 part S3 to 100 parts S10) which commences the process of end-to-end linkage of the molecules. This linking is enhanced at room temperature; however, it is very slow when kept in the freezer at -15°C to -25°C. The dehydrated specimen is submerged in the cold (-15°C to -25°C) polymer mixture. After some days of immersion, vacuum is applied to it. Vacuum is increased gradually to boil the intermediary solvent (acetone), which has a lower boiling point (56°C) out of the specimen. Impregnation is monitored by watching the bubble formation on the surface of the mixfure and by a vacuum gauge. Vacuum is complete when the pressure is around 5mm Hg. Equipment needed for forced impregnation includes a deep freezer (explosion proof or motor and compressor removed and placed in a different room), vacuum chamber (e.g. Heidelberg plastination kettle) and a vacuum pump with a pumping speed of 1.5 m3/min. for a 15 l polymer mixture or 3 m3/min. for a 30 l polymer mixture. Finally, the polymer inside the specimen has to be cured (hardened). This is achieved by exposing the impregnated specimen to a gaseous hardener (Biodur™ S6). S6 is a liquid that vaporizes at room temperature. The impregnated specimen and a bowl filled with S6 are placed in a tightly closed chamber for several weeks. To keep the environment for curing dehumidified a bowl with a desiccant (e.g. calcium chloride) is also placed in the curing chamber. To enhance the curing procedure, air may be bubbled through the fluid S6. For complete curing inside the specimen, the specimen should be kept in a plastic bag for several weeks. Equipment needed for curing includes a plastic or stainless steel box, stretch foil and membrane (aquarium) pump.
Epoxy (E12) procedure:
The E12 technique allows processing of fixed and unfixed fresh specimens. Kayserling solution is recommended for fixation. Others work as well. The specimens are initially frozen in a deep freezer. For best results, an ultra low deep freezer (-70°C) is recommended. With a special band saw, body parts are sliced into 2.5mm thick slices. After removing the saw dust, the slices are transferred to plastic grids. The grids containing the slices are placed into a steel basket for further procedures. The basket of slices is placed in acetone at -25°C. Three or four acetone baths are used subsequently to achieve complete dehydration. The basket of slices is transferred to a fresh E12 mixture (95pbw E12, 5pbw AT30, 20pbw AT10, 26pbw E1) and placed under vacuum for 24-48 hours at 0-10°C. The vacuum is increased until 5mm Hg is attained. The basket of slices is then removed from the vacuum chamber. Individual slices are placed between two glass plates. A silicone gasket is placed between the outer edges of the sheets and then clamped in position using fold-back clamps. The glass chambers containing the specimens are filled with a fresh E12 mixture (95pbw E12, 5pbw AT30, 26pbw E1). Following 2-3 days precuring at room temperature, the glass chambers are placed in a well-ventilated oven at 50°C for another 2-3 days. When curing is completed, the cold glass chambers are dismantled and the sections are trimmed on a band saw. After sawing, the edges are smoothed using a belt sander.
Polyester (P35) procedure:
Fresh brains are fixed the usual way with 10% formaldehyde for 4-6 weeks. Specimens which have been fixed by other methods should be avoided for this procedure because other fixation methods may interfere with the P35 reaction. After embedding in 20% gelatin (Barnett et al., 1980), brains are cut with a meat slicer into 4mm slices. To prevent disintegration of the slices after cutting and during subsequent handling, they are placed on a piece of wet filter paper before being transferred to stainless steel grids. The grids containing the slices are placed into a stainless steel basket for flushing. The basket of slices is rinsed with cold tap water overnight and cooled to 5°C before proceeding. The basket of slices is placed in 100% acetone at -20°C for 3 days. The basket of brain slices is placed in a bath containing a mixture of P35/A9 (100 parts P35 polymer and 2 parts A9 hardener) for one day at 5°C. This bath might be the 2nd immersion bath mixture of a previously run group of specimens. The basket of brain slices is placed in a second immersion bath containing a mixture of P35/49 (100:2) for a further 24 hours at 5°C. This bath might be the bath used for forced impregnation during for a previously run group of specimens. The basket of brain slices is transferred to a fresh P35/A9 mixture (100:2) and placed under vacuum for 24 hours at room temperature. The vacuum is increased until 10-15mm Hg is attained. The basket of slices is removed from the vacuum chamber. Individual slices are placed between two sheets of glass plates. Each sheet consists of an outer piece of safety glass and an inner sheet of float glass, the latter sheet facing the brain slices. A silicone gasket is placed between the outer edges of the sheets and the clamped in position using fold-back clamps. The double glass chambers containing the specimens are filled with a fresh P35/A9 (100:2) mixture. After casting, the double glass chambers are exposed to UVA light for 3 hours. During this procedure, it is necessary to cool the chambers either by ventilators or by blowing compressed air over both sides of the double glass chamber. Following light curing, the double glass chambers are placed in a well ventilated oven at 45°C for 5 days. When curing is complete, the glass chambers are dismantled and the sections are trimmed on a band saw. After sawing, the edges are smoothed using a belt sander.
Polyester (P40) procedure:
This technique has advantages over the others. P40 resin has a lower viscosity than the P35 resin. The advantages of using this technique are: 1. The same polymer can be used for immersion, impregnation, and casting of specimens. 2. Only single float glass chambers are necessary when casting specimens as compared with the expensive double glass chambers, containing safety glass, as in the P35 method. 3. P40 is cured by UVA light only; therefore, there is no requirement for an expensive ventilated heat cabinet as in the P35 method. 4. P40 can be used for production of transparent body slices as well as brain slices. The disadvantages associated with the P40 procedure occur during the curing process. UVA curing may be incomplete in brain tissue and will appear as orange discolored regions within the gray matter.

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The S10 procedure is the most widely used application in plastination. Specimen impregnation with Biodur™ S10, or similar products from other companies (Cor-Tech™ PR-10, Syl-Tech B, VisDocta™ SH-1) results in opaque, more or less flexible and natural looking specimens. The procedure consists of the four main steps of plastination: fixation, dehydration, forced impregnation and curing. Other steps may be added for special results. Specimens are fixed the usual way with 5-10% formaldehyde or other fixatives. Old, wet specimens can be used for the S10 procedure provided they are thoroughly washed with tap water. Hollow organs must be dilated with the fixative. Specimens are dissected as desired. Some cuts may better be done after curing to obtain smooth surfaces. Slicing can be done now, but may preferably be done after plastination (see step 4b). Hollow organs must not be cut; if windows are desired they may be cut after curing. Specimens are rinsed with cold tap water overnight and cooled to 5°C. This step is both important to get rid of the fixative and to pre-cool the specimens before dehydration. Additives (activator, cross-linker, thinner) and procedures (time, temperature, and method of application) may vary depending on the brand. Flexibility mainly depends on specimen thickness. Stomachs, intestines and thin tissue layers are more flexible than thick, parenchymal organs such as liver and kidney. Specimens are submerged in usually three subsequent baths of pure acetone at -20°C (10 l per 1kg specimen). Each dehydration bath should last about one week; however, the dehydration period may be extended to several weeks. Dehydration is finished when the acetone concentration is at least 99%. Complete dehydration at -20°C is necessary to avoid shrinkage. Dehydrated specimens are submerged in the S10/S3 mixture (1 part S3 hardener to 100 parts S10 polymer) for at least one day (up to several weeks) at -20°C. This additional step again prevents shrinkage. The longer specimens are immersed in the S10/S3 mixture, the shorter the following impregnation time will be. The submerged specimens are set on vacuum for three weeks at -20°C. Impregnation starts when large bubbles (=acetone) start to pop up to the surface of the silicone in the vacuum chamber (usually at about 150mm Hg). From this point on the vacuum must be gradually increased to 0mm Hg within the three weeks. The slower one goes, the better are the results. Fast impregnation causes shrinkage mainly in thick specimens because the polymer cannot be forced into the cells as fast as the acetone leaves them. After removal of excess polymer, the specimens are placed on a grid in an air tight chamber and exposed to S6 gas cure for about 7 days at room temperature. The vaporization of S6 is enhanced by bubbling air through the fluid S6 by means of small aquarium pumps or by the use of ventilators. This causes fast curing of the surface. To cure the polymer inside the specimen it is necessary to store the specimens in air tight plastic bags for up to two months. A small container with calcium chloride in the curing chamber collects moisture, which otherwise may cause white spots on the brain's surface. When the whole procedure is finished, the S10 plastinated specimens can be sliced with a band saw or a strong rotation meat slicer. After slicing the slices may be smoothed by sanding the slices on a belt sander, ideally with addition of water.

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To evaluate the scientific impact of plastination the New Plastination Index- Online (http://www.uqtr.ca/plastination/) is a helpful tool. During the years 1978-2005, a total number of about 1100 manuscripts have been published in more than 180 scientific journals and books. Most of the 553 original articles in peer-reviewed journals, 429 communications at scientific congresses and 87 other articles deal with plastination technology, teaching, public exhibition/ethics and sectional anatomy. The plastination method with the highest educational value is the most widely used silicone procedure. The sheet plastination techniques have the highest scientific impact in both scientific teaching and research in sectional anatomy. The scientific application of sheet plastination usually requires hightech equipment such as equipment for special staining techniques (plastination histology) and slicing devices before impregnation (ultra low temperature deep freezers, stainless steel band saws, and rotation meat slicers) and after impregnation (diamond band and diamond wire saws). One major application of sheet plastination is the study of tissue patterning because the delicate structures particularly of connective and muscular tissue are easily damaged or altered during dissection and histological examination is limited by the sample size. Sheet plastination on the one hand does not destroy the tissues and on the other hand the sample size is not limited as in histology. Thus, sheet plastination offers a new approach to study tissues at both macroscopic and microscopic levels and thus provides a tool to close the gap between macro- and microstructure.

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