两种方法制备的脑组织切片激光共聚焦显微镜成像效果的比较研究

该文比较研究了振动切片法与冰冻切片法制作的脑组织切片的质量及其激光共聚焦显微镜成像的效果。振动切片法通过灌流固定、取小鼠脑、琼脂糖包埋后利用振动切片机连续冠状切片。冰冻切片法通过蔗糖脱水、OCT包埋液氮骤冷后利用冰冻切片机连续冠状切片。制备的脑组织切片进行免疫荧光染色,激光共聚焦显微镜观察成像效果。结果表明,与冰冻切片相比,振动切片法简单快速,且制片质量较高,脑组织切片无冰晶形成,抗原免遭破坏,组织结构较完整,更适用于脑组织样品的激光共聚焦显微镜的成像观察。     

采用卵巢冰冻切片和改进H&ampE染色方法分析小鼠发情周期卵泡形态

本研究目的在于改进现有的卵巢组织切片及染色方法,建立更快观察和评价卵巢组织中各级卵泡数量和质量的方法。取动情前期、动情期、动情后期和动情间期雌性C57BL/6J小鼠卵巢,用4%多聚甲醛固定,梯度蔗糖脱水,OCT(optimal cutting temperature compound)包埋,冰冻切片(厚7 μm),快速HampE染色后进行观察。结果显示,本方法能够分辨次级卵泡、窦前、窦状和排卵前卵泡,虽然不能区分和分辨始基卵泡和初级卵泡,但是其它观察结果与复杂的方法相当。以上结果提示,快速和改进的小鼠卵巢冰冻切片和HampE染色方法可以与激素分析结合,用于小鼠模型中的卵巢发育和功能研究。     

采用卵巢冰冻切片和改进H&E染色方法分析小鼠发情周期卵泡形态（英文）

通过观察卵巢组织中不同发育阶段的各级卵泡的形态和数量,并结合促性腺激素和性激素的测定能够更好地评估卵巢功能。本研究目的在于改进现有的卵巢组织切片及染色方法,建立更快观察和评价卵巢组织中各级卵泡数量和质量的方法。取动情前期、动情期、动情后期和动情间期雌性C57BL/6J小鼠卵巢,用4%多聚甲醛固定,梯度蔗糖脱水,OCT(optimal cutting temperature compound)包埋,冰冻切片(厚7μm),快速HE染色后进行观察。结果显示,本方法能够分辨次级卵泡、窦前、窦状和排卵前卵泡,虽然不能区分和分辨始基卵泡和初级卵泡,但是其它观察结果与复杂的方法相当。以上结果提示,快速和改进的小鼠卵巢冰冻切片和HE染色方法可以与激素分析结合,用于小鼠模型中的卵巢发育和功能研究。     

三种不同脂肪染色方法的比较

目的探讨碳蜡(聚乙二醇)包埋技术、冰冻切片及饿酸染色在脂肪染色中的应用,综合比较几种方法的优缺点,以便在病理工作及科研工作中能找到更适合的脂肪染色方法。方法取新鲜脂肪组织及肝组织,每份标本各取3块组织,分为A、B、C三组:A组和B组标本分别进行碳蜡包埋切片和常规冰冻切片,油红O法染色;C组以饿酸浸染组织块后进行石蜡包埋切片及眦复染。结果 A组切片脂肪滴呈红色,细胞核呈蓝色;B组切片脂肪滴呈红色,细胞核呈蓝色;C组切片脂肪滴呈黑色。结论饿酸染色和碳蜡包埋技术在脂肪染色中,具有冰冻切片和石蜡切片的优点,弥补了常规冰冻切片脂肪染色的缺点和局限性,在病理检验及科研中具有一定应用价值。     

一种简单快速植物组织冰冻切片方法

比较不同冷冻方法对植物细胞超微结构的影响,结果表明:直接包埋法处理的植物细胞超微结构保存较好,而液氮冷冻处理的植物细胞内膜系统损伤严重.建立了一种直接包埋冷冻和适当回温相结合的方法,不仅可以制作出植物细胞基本结构保存完整的组织切片,而且避免了使用冰冻保护剂的弊端.其操作程序是:样品固定→冰冻与包埋→适当回温→快速切片→展片→染色.此法制作的切片可进行不同的染色和组织细胞化学测定,具有操作简便,易于推广的特点.     

常温和低温下保存小新月菱形藻的包埋-脱水法

用包埋.脱水法在常温和低温下保存小新月菱形藻(Nitzschla closterium f.minutissima),探讨了温度、光(暗)、含水量,密封袋内空间体积和密封袋外膜材质等因素对保存效果的影响.结果表明,小新月菱形藻在4℃下暗保存6个月后的最高存活率达到80.4%.而且,保存后的藻细胞经过恢复培养后,其生长力可达到保存前的水平.包埋.脱水法操作简单.无需复杂设备,在藻类种质保存中有广阔的应用前景.     

包埋-脱水法常温和低温保存绿色巴夫藻

用包埋-脱水法在常温和低温下保存绿色巴夫藻(Pavlova virdis),探讨了温度、光(暗)和含水量等因素对存活率的影响.结果表明,通过调节含水量、控制光(暗)条件以及使用甘油保护剂等措施,绿色巴夫藻在常温和低温下都可以保存6个月并保持较高的存活率.其中4℃(暗)保存的最高存活率高达77.6%,而且保存后的藻细胞经过适当的恢复培养后,其生长力可以达到保存前的水平.包埋-脱水法操作简单,无需贵重设备,在藻类种质保存中有广阔的应用前景.     

微小组织冰冻快速制片技术

目的摸索提高微小组织冰冻快速制片质量的方法。方法针对小组织冰冻切片中常常出现组织切完、多粒组织切片不全、冰晶、染色不均匀等问题,采用预先制作冷冻平台、快速冷冻等方法来制作优质的冰冻切片。结果组织铺平可使组织切片完整,快速冷冻可减少冰晶形成,使组织结构更清晰,及时固定和加温染色可使细胞核染色更鲜艳,核、质对比明显。结论组织铺平、速冻、固定、染色等都是提高微小组织制片质量的关键。     

碱性磷酸酶钙-钴法染色的不同包埋方法比较

目的探讨石蜡切片、冰冻切片及碳蜡(聚乙二醇)包埋切片在碱性磷酸酶染色中的应用,综合分析几种组织处理方法的优缺点,以便在病理诊断及科研工作中能找到更适合的碱性磷酸酶染色方法。方法取新鲜乳腺组织及肝组织,每份标本各取3块组织,根据包埋方法的不同,分为3组:石蜡切片碱性磷酸酶染色、冰冻切片碱性磷酸酶染色、碳蜡包埋切片碱性磷酸酶染色。结果 3组切片均可见黑色碱性磷酸酶的存在,其中肝组织内显示碱性磷酸酶呈黑色,沿胆小管分布;乳腺组织内显示碱性磷酸酶呈黑色沉淀弥漫分布于乳腺间质中。结论碳蜡包埋切片在碱性磷酸酶染色中,具有冰冻切片和石蜡切片的优点,并弥补了常规冰冻切片和石蜡切片染色的缺点和局限性,在病理诊断及科研工作中具有一定的应用价值。     

火棉胶包埋组织切片及冰冻切片的连续切片与染色

近年来为了教学和研究所用之切片标本,曾广泛使用火棉胶包埋组织切片和冰冻切片法,这两种方法虽然它是有比石腊包埋组织切片稍厚一点,但它的优点是远超过了缺点。组织用石腊包埋,在组织经过不同浓度酒精脱水后,须用氯仿或二甲苯透明,再置于58℃温箱石腊中几个小时。以上透明剂具有使组织收缩变小,在经过这样高温之下,组织增加它由收缩而扭转和变形,纤维曲折,细胞及所含物质缩小,折光率增强,组织内所含之尖脂脂亦易于被以上透明剂所溶解,致染色不佳。作为观察和研究组织形态是不够美满的。因为石腊包埋组织制作切片有以上之缺点,     

A comparison of cryo- versus chemical fixation in the soil green algae Jaagiella

Chemical fixation protocols provided unsatisfactory preserved material for ultrastructural studies on Jaagiella alpicola Vischer (Chlorophyta). Instead, several methods of rapid freeze fixation followed by freeze substitution were applied. For fast freeze fixation, two methods were tried: plunge immersion freezing in liquid propane using a home-made device, and projection against a copper block cooled by either liquid nitrogen or liquid helium. Each method furnished well fixed material. The quality of the fixed samples was quite similar whether propane or the cryoblock cooled with liquid nitrogen was used. Liquid helium, however, provided superior results. After fixation the samples were cryosubstituted, using acetone or methanol as organic solvent with a chemical fixative added. Acetone gave better results than methanol as a substitution solvent when high temperature embedding was performed. The best cryosubstitution for ultrastructural studies was that in which osmium tetroxide or a mixture of osmium tetroxide and urany acetate was used.     

Self-pressurized rapid freezing (SPRF) as a simple fixation method for cryo-electron microscopy of vitreous sections

Cryo-electron microscopy of vitreous sections (CEMOVIS) is currently considered the method of choice to explore cellular ultrastructure at high resolution as close as possible to their native state. Here, we apply a novel, easy-to-use and low-cost freeze fixation method for CEMOVIS, avoiding the use of high-pressure freezing apparatus. Cells are placed in capillary metal tubes, which are tightly closed and plunged directly into liquid ethane cooled by liquid nitrogen. In some parts of the tube, crystalline ice is formed, building up pressure sufficient for the liquid-glass transition of the remaining specimen. We verified the presence of vitreous ice in these preparations using CEMOVIS and electron diffraction. Furthermore, different tube materials being less poisonous than copper were established to minimize physiological alterations of the specimen. Bacteria, yeast and mammalian cells were tested for molecular resolution. The quality of results is equivalent to samples prepared by conventional high pressure freezing apparatus, thus establishing this novel method as fast, easy-to-use and low-cost freeze fixation alternative for cryo-EM.     

Ultrastructural observations on tissues processed by a quick-freezing,rapid-drying method: Comparison with conventional specimen preparation

A quick-freeze, rapid-dry method for processing unfixed tissue for electron microscopy has been developed. The technique employs freezing on a cryogenchilled metal surface and drying in a cryosorption vacuum apparatus that allows osmium-vapor fixation and epoxy-resin embedment under high vacuum. Liver, kidney, bone marrow, and monolayer cultures of ventricular myocytes were selected as tissue specimens representing a wide range of physical properties, to demonstrate the practical aspects of achieving good ultrastructural morphology by freeze drying. A comparison was made between freeze drying and conventional processing using aldehyde fixation and alcohol dehydration. The preservation of cellular ultrastructure achieved by freeze drying allowed the identification of specific cell types within each specimen. Membranous organelles were well preserved, surrounded by cytoplasmic ground substance devoid of ice crystal damage. Electron-dense material was observed within the rough endoplasmic reticulum and Golgi cisternae and vesicles of frozen-dried, but not conventionally processed cells. This suggests the preservation by freeze drying of cytoplasmic components otherwise extracted from the cell by solvent exposure.     

Quench cooling and ice crystal formation in biological tissues

The rates of cooling of tissue packages quenched in liquid nitrogen were investigated using microthermocouples. By assembling tissue packages from a standard 200-μm tissue slice a microthermocouple could be positioned at different depths within the package. Results showed that for a given mass of tissue the rates of cooling at different depths were the same. When the tissue mass was varied the rates of cooling at a fixed depth decreased with increasing tissue mass.The ice crystal formations produced when tissues are quenched in liquid nitrogen were investigated using freeze substitution. Assemblies of rabbit cornea of different thicknesses were quenched in liquid nitrogen and freeze substituted. The size of the ice crystal cavities produced during the quenching increased with increasing tissue mass, exhibiting a saturation size for the larger tissue masses. There was no obvious size distribution of the ice crystal cavities across the thickness of the corneas.The results suggest an “isotherm” model for the quenching conditions used in these experiments, there being small or negligible temperature gradients through the tissue which uniformly cools at a fixed rate.     

Long term effects of cryosurgery on cutaneous sensation.

In a study of the time course and nature of the sensory loss after cryosurgery the forearms of nine normal subjects were treated with liquid nitrogen using freeze times currently employed in clinical practice in Britain. Ability to appreciate touch, pinprick, and cold in the treated areas was tested at regular intervals and biopsy samples taken to investigate the pathogenesis. Appreciation of all three modalities of sensation was initially reduced in all nine subjects for all freeze times, yet complete recovery occurred in the seven patients completing follow up. This recovery, however, took up to one and a half years for the longest freeze, with even a 10 second freeze taking up to 10 months. Patients may be reassured that sensory loss after cryosurgery for up to two periods of 30 seconds will almost certainly recover, though it may take up to 18 months to do so.     

Freezing injury: the special case of the sperm cell

The cellular damage that spermatozoa encounter at rapid rates of cooling has often been attributed to the formation of intracellular ice although no convincing evidence of intracellular ice formation has ever been obtained. We demonstrate that the high intracellular protein content together with the osmotic shrinkage associated with extracellular ice formation leads to intracellular vitrification of spermatozoa during cooling. At rapid rates of cooling the cell damage to spermatozoa is a result of an osmotic imbalance encountered during thawing, not intracellular ice formation. The osmotic imbalance occurs at rapid cooling rates due to a diffusion limited ice crystallisation in the extracellular fluid, i.e. the amount of ice forming during the cooling is less than expected from the equilibrium phase diagram. This explanation allows insights into other aspects of the cryobiology of spermatozoa and it is anticipated that this understanding will lead to specific improved methods of conventional cryopreservation for mammalian spermatozoa. It is also likely that this model will be relevant to the development of novel technologies for sperm preservation including vitrification and freeze drying.     

Stabilization of frozen Lactobacillus delbrueckii subsp. bulgaricus in glycerol suspensions: Freezing kinetics and storage temperature effects

The interactions between freezing kinetics and subsequent storage temperatures and their effects on the biological activity of lactic acid bacteria have not been examined in studies to date. This paper investigates the effects of three freezing protocols and two storage temperatures on the viability and acidification activity of Lactobacillus delbrueckii subsp. bulgaricus CFL1 in the presence of glycerol. Samples were examined at -196 degrees C and -20 degrees C by freeze fracture and freeze substitution electron microscopy. Differential scanning calorimetry was used to measure proportions of ice and glass transition temperatures for each freezing condition tested. Following storage at low temperatures (-196 degrees C and -80 degrees C), the viability and acidification activity of L. delbrueckii subsp. bulgaricus decreased after freezing and were strongly dependent on freezing kinetics. High cooling rates obtained by direct immersion in liquid nitrogen resulted in the minimum loss of acidification activity and viability. The amount of ice formed in the freeze-concentrated matrix was determined by the freezing protocol, but no intracellular ice was observed in cells suspended in glycerol at any cooling rate. For samples stored at -20 degrees C, the maximum loss of viability and acidification activity was observed with rapidly cooled cells. By scanning electron microscopy, these cells were not observed to contain intracellular ice, and they were observed to be plasmolyzed. It is suggested that the cell damage which occurs in rapidly cooled cells during storage at high subzero temperatures is caused by an osmotic imbalance during warming, not the formation of intracellular ice.     

Importance of the Fixative for Reliable Ultrastructural Preservation of Poikilohydric Plant Tissues. Observations on Dry, Partially, and Fully Hydrated Tissues ofSelaginella lepidophylla

Leaves of desiccated ‘resurrection plants’,Selaginellalepidophylla, were hydrated either through the roots of intactplants or as isolated organs. Air-dry tissue and samples at1, 4, 8 and 24 h (both detached and intact) of hydration wereprepared for electron microscopy using aldehyde fixatives ofdifferent osmotic strengths. Both dry and hydrated tissues werealso prepared using freeze substitution. Significant differencesin the ultrastructural preservation of these different sampleswere noted. There was a direct correlation between the osmolalityof both the fixative and the tissue with the quality of ultrastructuralpreservation. When the osmolality of the fixative was slightly(or even considerably) higher than that of the tissue, optimalpreservation was achieved. Freeze substitution, however, gavethe most faithful preservation of all subcellular compartments,despite the frequent presence of small ice crystals. Additionally,hydration of detached leaves for more than 4 h resulted in swellingdamage of the organelles and cytoplasm, regardless of the fixationprotocol. Broadly interpreted, the results of this study indicate thatan optimal preservation of plant cell and organelle ultrastructurecan be achieved by the use of high osmolality fixatives or,preferably, freeze substitution. These results are also importantin determining the method of hydration of poikilohydric samplesfor physiological studies and for interpretation of functionalchanges as related to the structural condition of the organelles.Copyright1997 Annals of Botany Company Selaginella; fixation; ultrastructure; dry; hydrated     

Large Ice Crystals in the Nucleus of Rapidly Frozen Liver Cells

Evidence in the literature shows that ice crystals that form in the nucleus of many rapidly cooled cells appear much larger than the ice crystals that form in the surrounding cytoplasm. We investigated the phenomenon in our laboratory using the techniques of freeze substitution and low temperature scanning electron microscopy on liver tissue frozen by liquid nitrogen plunge freezing. This method is estimated to cool the tissue at 1000°C/min. The results from these techniques show that the ice crystal sizes were statistically significantly larger in the nucleus than in the cytoplasm. It is our belief that this finding is important to cryobiology considering its potential role in the process of freezing and the mechanisms of damage during freezing of cells and tissues.     

Cryopreservation of Embryogenic Suspension Cultures of Barley (Hordeum vulgare L.)*

Anther-derived suspension cultures of Hordeun vulgare L. were cryopreserved by slow cooling and storage in liquid nitrogen for up to 55 days. Cells were pre-cultivated in L3 suspension medium supplemented with sorbitol. For freeze preservation the cells were treated with different combinations of cryoprotectant agents such as DMSO, proline, glycerol and sucrose. After rapid thawing high viabilities of up to 77% could be achieved. Cell growth commenced 2- 3 weeks later. The frequency of plantlet regeneration was 1%.