Multiple polymer plastination: Combining different types of polymers in teaching and exhibition plastinates

Vacuum forced tissue impregnation is the signature step of the plastination process. It requires polymers with a low vapour pressure, low viscosity and a long pot life. Plastination polymers are a compromise between these mandatory requirements on the one hand and various secondary demands such as specimen stability, resistance to UV light and defined light refraction index on the other hand. Combining different polymers in one plastinate instead of using one plastination polymer alone can result in improved specimens for exhibitions and teaching including hands‐on use for students. The aim of this study was to assess the range of possible sheet plastinate modifications and how the resulting multiple polymer plastinates can fulfil the secondary requirements of user‐friendly plastinates. Adding sub‐steps of tissue impregnation and processing to the standard plastination protocol allows combining different polymer properties including the use of substances which are not suitable for conventional plastination as such but have better properties than plastination polymers. Advantages like resistance to UV light and mechanical stability can be combined and characteristic disadvantages of plastination polymers can be avoided. Acrylic protection layers (APL) offer a complete protection of the specimen in combination with advanced presentation possibilities and the option of completely refurbishing valuable specimens. Hybrid sheet plastinates provide lower preparation cost and polymer–tissue interactions for an improved visualization of fat, nerves and brain tissue. Selective impregnation is a promising approach for the clearer differentiation of various structures and tissue types.     

P40 polyester sheet plastination technique for brain and body slices: The vertical and horizontal flat chamber methods

The P40 technique produces high‐quality brain and body slices and is the user‐friendliest of the polyester techniques. The P40 polyester technique follows the same classical steps for plastination. That is, preparation of the specimen, fixation (optional), dehydration by freeze substitution, forced impregnation and curing. Two methods used to prepare two different types of specimens, that is, brain slices and body slices are described. Each method has its own characteristics depending on the specimen type used. Brain slices were used to illustrate the vertical small chamber method while the body slices were used to illustrate the horizontal large chamber method. The brain slices obtained using P40 are of very good quality presenting good contrast between grey and white matter. The body slices are also of very good quality. The physical appearance of these slices makes them an exceptional instrument for diagnostic imaging and anatomical correlation. Body slices prepared with P40 retain the natural colour of the tissue and preserve the anatomical relationships.     

Work safety in plastination

In this article, information is given on potential physical and health hazards in the steps of the silicone cold temperature method, often referred to as “S 10 Standard Method.” The main potential hazards related to plastination, as well as recommended measures to effectively avoid explosion and health hazards are discussed. Some specialty chemicals pose chronic health hazards. Exposure to these chemicals can be avoided by standard laboratory hygiene, that is wearing personal protective equipment like safety goggles and protective gloves. Inhalation hazard, for example when working at open dehydration containers or when opening a gas curing box, is preferentially avoided by the action of an appropriate ventilation system. Acetone is the standard solvent used for dehydration and defatting of the specimens to be plastinated. Like for other flammable liquids, explosion protection must be considered when handling acetone. The concentration of acetone vapour in the air must be kept below the lower explosion limit through appropriate room or workplace ventilation. Furthermore, all potential sources of ignition should be removed from the explosion hazard zone. If electrical devices need to be operated inside the explosion hazard zone, they need a special design and approval. The conditions covered by this approval can be found on the identification plate of the individual device.     

E12 technique: Conventional epoxy resin sheet plastination

Epoxy plastination techniques were developed to obtain thin transparent body slices with high anatomical detail. This is facilitated because the plastinated tissue is transparent and the topography of the anatomical structures well preserved. For this reason, thin epoxy slices are currently used for research purposes in both macroscopic and microscopic studies. The protocol for the conventional epoxy technique (E12) follows the main steps of plastination—specimen preparation, dehydration, impregnation and curing/casting. Preparation begins with selection of the specimen, followed by freezing and slicing. Either fresh or fixed (embalmed) tissue is suitable for epoxy plastination, while slice thickness is kept between 1.5 and 3 mm. Impregnation mixture is made of epoxy E12 resin plus E1 hardener (100 ppw; 28 ppw). This mixture is reactive and temperature sensitive, and for this reason, total impregnation time under vacuum at room laboratory temperature should not last for more than 20–24 hr. Casting of impregnated slices is done in either flat chambers or by the so‐called sandwich method in either fresh mixture or the one used for impregnation. Curing is completed at 40°C to allow a complete polymerization of the epoxy‐mixture. After curing, slices can be photographed, scanned or used for anatomical study under screen negatoscope, magnification glass or fluorescent microscope. Based on epoxy sheet plastination, many anatomical papers have recent observations of and/or clarification of anatomical concepts in different areas of medical expertice.     

Room temperature/Corcoran/Dow Corning™—Silicone plastination process

For 20 years, the cold temperature/S10/von Hagens' plastination technique was used to preserve biological specimens without challenge. It became the “gold standard” for preservation of beautiful, dry biological specimens. Near the end of the 21st century, a group from the University of Michigan and environs and Dow Corning?, USA, combined silicone ingredients, similar to the von Hagens' plastination products, however in a different sequence. The new polymer (Cor‐tech) was combined with the cross‐linker to design the “impregnation mix” which would invade the cellular structure of the specimen and yet was stable at room temperature. Later, curing would be by application of the catalyst onto the impregnated specimen. This unique sequencing of products would become the “Room temperature/Dow Corning?/Corcoran—Silicone plastination technique.” The results of this room temperature technique provided similar plastinates, beautiful and practical for demonstration, containing no toxic chemical residues and forever preserved. As the name implies, impregnation of this silicone mix could be done at room temperature, without having to be kept cold. Both processes (cold and room temperature) required the same four basic steps for plastination. As well, both processes used similar basic polymers and additives to produce plastinates. However, they were combined in a different sequence. Cold temperature combines polymer and catalyst/chain extender, which is not stable and therefore must be kept colder than ?15°C, while room temperature combines polymer with cross‐linker which is stable, and likely forever.     

Cold temperature/Biodur®/S10/von Hagens'—Silicone plastination technique

Plastination is a late 20th century preservation methodology which replaces tissue fluid within a specimen with a curable polymer, such as silicone. Plastination yields superb, beautiful, well‐preserved specimens each with their own unique qualities. Silicone polymer is used around the world to preserve macroscopic cadavers or portions/organs thereof. Plastination was conceived by Dr. Gunther von Hagens, Universität Heidelberg, Heidelberg, Germany prior to 1977. Silicone polymer was the primary polymer which emerged initially for plastination. The Biodur^® line of silicone polymer and additives was chosen and manufactured because it has consistently produced the best plastinates since the inception of plastination. Since the discovery of silicone, generic and similar silicone polymers are known and used around the World by many industries and used in numerous products. The plastination process has four steps: Specimen preparation, Specimen dehydration and degreasing, Vacuum‐forced impregnation of specimens and Specimen hardening.     

中国草业教育发展史:2.研究生教育

中国的草业科学研究生教育开始于1951年,较本科专业早7年,也是较早启动研究生教育的学科之一。近60年来,历经了非学位研究生教育(1951～1976年)和学位研究生教育(1978年至今)两个阶段的发展,培养和研究的方向从牧草学和草原学,扩展和覆盖到环境生产、植物生产、动物生产、工贸生产4个生产层的诸多方面;专业的名称也由草原科学改为草业科学。研究生教育在内涵提高的同时,外延也得到了很大的扩展,学科点的数量和培养规模大幅度增加,2010年全国共有草业科学硕士点38个,博士点19个,覆盖全国27个省市自治区;有硕士生导师232人,博士生导师107人。已毕业硕士生1 643名,博士生328名;在读硕士生1 114名,博士生319名。我国已成为世界上同类专业中教学指导思想先进,培养层次完整、学科点和学生数量最多的国家。     

张掖市肉牛发展历史和现状及国内外肉牛发展经验借鉴

本文通过对张掖肉牛发展历史、现状的分析,总结了目前国内外肉牛产业发展的成功经验,旨在探讨张掖肉牛发展的新思路和新举措,在现代畜牧业生产技术创新中具有现实的指导意义。     

中国高等草业教育的历史、现状与发展

中国草业本科教育经历了单门课程教学、本科专业体系初步形成和教育体系完善三个发展阶段。1958年建立了第一个本科专业。目前全国约有本科专业24个。研究生教育开始于1951年。现在已形成专科、本科、硕士、博士、博士后五个完整的高等教育层次。在中国当前新的历史条件下,高等草业教育的特点是,专业发展十分迅速,空间布局均匀、合理,在具有中国特色的先进草业科学理论指导下,教学内容获得明显的扩大和提升。存在的主要问题是,随着草业和生态环境建设的发展,在草业科学本科一级学科之下,需要考虑建立二级专业;明确各教育层次的培养目标和服务对象,有区别地培养配套人才;加强师资建设,保证教学质量;加强国际草业教育交流,迅速在整体上达到世界草业教育先进水平。     

中国草业教育发展史:1.本科教育

中国现代意义上的草业教育是从高等教育开始,由20世纪30年代在大学陆续开设的牧草学、草原学、饲料生产学等单门课程逐步发展、扩大为完整、系统的草业科学专业。70多年来,通过单门课程教学,本、专科专业教学体系初步形成,恢复及完善,本科专业教学体系快速发展和提高4个发展阶段,草业教育由畜牧专业的单门课程发展为独立的二级专业,继由二级专业提升为草业科学一级学科。草业本科教育在内涵提高的同时,其外延也取得了巨大的发展与成就,专业的数量和培养的草业人才大幅度增加,2010年全国共有草业科学本科专业30个,截至2008年底,有专业教师486人,已毕业本专科生14 225名,有在读本科生5 107名,中国成为世界上草业科学专业和学生的数量最多、培养层次最完整、教学指导思想最先进的国家之一,而且,甘肃农业大学的草业科学本科专业是世界上规模最大的本学科本科专业。     

Ultra‐thin sectioning and grinding of epoxy plastinated tissue

With classical sheet plastination techniques such as E12, the level and thickness of the freeze‐cut sections decide on what is visible in the final sheet plastinated sections. However, there are other plastination techniques available where we can look for specific anatomical structures through the thickness of the tissue. These techniques include sectioning and grinding of plastinated tissue blocks or thick slices. The ultra‐thin E12 technique, unlike the classic E12 technique, starts with the plastination of a large tissue block. High temperatures (30–60°C) facilitate the vacuum‐forced impregnation by decreasing the viscosity of the E12 and increasing the vapour pressure of the intermediary solvent. By sectioning the cured tissue block with a diamond band saw plastinated sections with a thickness of <300 μm can be obtained. The thickness of plastinated sections can be further reduced by grinding. Resulting sections of <100 µm are suitable for histological staining and microscopic studies. Anatomical structures of interest in thick plastinate slices can be followed by variable manual grinding in a method referred to as Tissue Tracing Technique (TTT). In addition, the tissue thickness can be adapted to the transparency or darkness of tissue types in different regions of the same plastinated section. The aim of this study was to evaluate the advantages of techniques based on sectioning and grinding of plastinated tissue (E12 ultra‐thin and TTT) compared to conventional sheet‐forming techniques (E12).     

国内外动物福利的发展历史及现状

作者总结了国内外动物福利的发展历史及现状,针对我国动物福利的现状提出一些切实可行的建议,为我国的动物福利提供理论依据,以推动我国畜牧业良性发展。     

A Brief History and Overview of Toxoplasma gondii

Toxoplasma gondii was discovered by scientists working in North Africa and Brazil around 100 years ago. The parasite has since been found to be capable of infecting all warm‐blooded animals including humans making it one of the most successful parasitic organisms worldwide. The pathogenic potential of T. gondii was recognized in the 1920s and 1930s, in congenitally infected children presenting with the classic triad of symptoms, namely hydrocephalus, retinochoroiditis and encephalitis. In addition, around the same time T. gondii parasites were found to be associated with severe intraocular inflammation. In the 1980s, T. gondii emerged as a major cause of death in patients with acquired immunodeficiency syndrome, illustrating the importance of the immune system in controlling T. gondii infection. T. gondii was reported as a major cause of abortion in sheep in New Zealand in the 1950s, which raised questions about potential new transmission routes for the parasite. The discovery of the cat as the definitive host in the 1960s was a very important finding as it helped to complete our understanding of the parasite’s life cycle, and the oocyst stage of T. gondii shed in the faeces of infected cats was found to be an important source of infection for many intermediate hosts and helped to explain infection in herbivorous animals and people with a vegetarian diet. In addition, this stage of the parasite was very robust and could survive in the environment, depending on the climatic conditions, for up to 12–18 months. Knowledge of the parasite’s lifecycle, transmission routes, risk groups and host immune responses has helped in the development of strategies to control the disease, reduce transmission of the parasite and limit environmental contamination.     

邓川牛养殖历史与现状探讨

邓川牛主产于洱源邓川地区,是当地白族人民在长期的养殖过程中培育的以乳用为主的我国地方黄牛良种,具有耐粗饲、适应性强、抗病力强、乳质佳等优良种质特征。近年随着杂交改良的进行,纯种邓川牛数量日益减少,保护邓川牛品种资源,在当下十分必要而紧迫,对促进当地经济可持续发展具有重要意义。     

中国古代养兔发展史

从化石和历史文献角度概述了我国古今存在的兔种,分析了我国家兔起源驯化过程,并通过历代对兔的记载纵观我国养兔发展,为我国家兔起源及驯化历史提供一定参考依据。     

History of the Australian college of veterinary scientists

The Australian College of Veterinary Scientists (ACVSc) has been promoting the advancement of the veterinary profession for 40 years through the provision of continuing education of Australian and New Zealand veterinarians. Formed in 1971 through the Australian Veterinary Association, after many years of debate over its role and necessity, the ACVSc became an independent entity in 1985. It currently provides examination-based qualifications of Membership and Fellowship of the College in 37 disciplines and has over 100 applicants every year. Highly valued as a mark of superior achievement in a veterinary field in Australia and New Zealand, the ACVSc is now working to have its Fellowship and Membership qualifications recognised in Europe and North America, thereby increasing the standing of Australian veterinarians around the world.     

可持续发展及荒漠绿洲林业可持续发展研究

在明确了可持续发展的概念、内涵基础上，综述了国内外林业可持续发展研究动态；从绿洲概念、特点及内涵出发，综述了荒漠绿洲林业可持续发展的研究现状，指出今后应从景观生态学角度研究绿洲林业可持续发展问题。     

内蒙古三河牛培育历程及进展

内蒙古三河牛是我国自主培育的乳肉兼用型品种,它是呼伦贝尔各族人民一百多年来辛勤劳动的结晶。从1986年育成以来,三河牛以核心家系选育的方式延续严格的保种制度,在呼伦贝尔草原严酷环境中保持良好的生产性能和繁殖力。虽然在近20年不断受到荷斯坦牛等高产品种的挑战,但对当地气候的高度适应性和良好的兼用性让三河牛始终立于不败之地。十一五以来,三河牛选育进一步得到国家重视,在原有品种登记和性能测定系统的基础上,修定并发布了新的三河牛品种国家标准,建立了三河牛育种信息数据库,引入奶牛DHI测定体系,强调兼用性的育种目标,吸收国外兼用型品种高水平遗传种质,采用开放式核心群育种体系,不断取得各方面进展。现简述三河牛培育历程,并总结目前的各项进展,与业界同仁分享。     

从猎杀到保护:美国历史上的野生动物

征服自然的思想在美国一直占主流,自然资源的开发是美国繁荣的基础。野生动物的猎杀是美国历史中的重要一幕,并产生了深远的影响。19世纪末20世纪初出现的动物保护活动是对滥杀动物所造成的恶果的反省,此后,社会对野生动物的态度有所转变,但动物保护仍面临严峻挑战。本文介绍美国历史中野生动物被猎杀的过程,提出一些值得思考的问题,如美国野生动物保护的局限性、野生动物猎杀与工厂化动物饲养的关系,以及伦理学在动物保护中的重要性。     

我国养鸡业历史回顾及未来发展趋势

１我国养鸡业的历史回顾１．１我国养鸡业的起源我国是世界上养禽历史最古老的国家，起源于新石器时代的早期，时间大约可以追溯到七千多年以前。在奴隶社会向封建社会过渡时期，我国的养禽业就已经十分发达了。据１９６３年我国考古研究所出版的《京山屈家岭》一书中就报道，在湖北省京山县屈家岭出土陶鸡，据１９８１年我国《考古学报》上发表的在河北武安县磁山文化遗址出土的文物中，有鸡的上膊骨、尺骨、锁骨、胫骨和跗跖骨等，又据１９８４年《考古发掘研究》中报道，在河南新郑县裴李岗出土了鸡的跗骨，并经放射性碳素分析，研究者对…