Perda de amostras em tissue microarray: comparação entre técnicas com uso de fita adesiva comercial, lâminas silanizadas pelo método tradicional ou por método modificado / Loss of tissue samples in the tissue microarray: comparison between techniques using commercial adhesive tape, silane-coated microslides by the conventional method and by a modified technique

Introdução/objetivo: O microarranjo tecidual, ou tissue microarray (TMA), permite avaliar múltiplas amostrasde tecido em um único bloco. Um dos problemas do TMA é o descolamento dos cortes teciduais, por isso, para reduzir essa perda, tem-se utilizado fita adesiva especial comercial. Não há relatos comparando o uso dessas fitas adesivas com a técnica de silanização modificada. O objetivo desse estudo foi comparar as perdas de cortes entre lâminas usando fitas adesivas comerciais, lâminas silanizadas por técnica convencional elâminas silanizadas por técnica modificada, com menor consumo de acetona. Material e método: O TMA foiconstruído com blocos de tecido hepático, em dispositivo de base fixa, colocando-se 32 cilindros de 2 mmde diâmetro em duplicata e espaçamento de 2,2 mm. Quinze secções de 4 μm foram colocadas em lâminas silanizadas a 4% por técnica convencional (grupo 1), 15 em lâminas silanizadas com técnica modificada (6%de silano e com uso mínimo de acetona) (grupo 2) e 15 em lâminas com fita adesiva comercial de acordo comas recomendações do fabricante (grupo 3). Todas as lâminas foram processadas por imuno-histoquímica para citoqueratina 18, com recuperação antigênica em tampão citrato pH 6, em microondas. As perdas de amostrasforam quantificadas e expressas como: perda total (≥ 80%), quase total (75% a 79%) ou parcial (50% a 74%).Resultados: A perda de tecidos foi semelhante nos três grupos: com silanização tradicional, modificada oufita adesiva comercial (4,9 vs. 3,1 vs. 8,1, respectivamente) (análise de variância [ANOVA], p = 0,3654). Umadas lâminas com a fita adesiva apresentou descolamento artefatual de todos os tecidos e outra de 20 tecidosem um dos lados. Nenhuma das lâminas silanizadas apresentou tal artefato. Conclusão: Lâminas silanizadas têm resultados satisfatórios, requerem menos treinamento técnico e reduzem os custos da utilização do TMA justificando seu uso em pesquisa...

Introduction/objective: The tissue microarray (TMA) technique allows the evaluation of multiple tissue samplesin a single block. One of the problems of TMA is the ungluing of tissue sections, thus commercial adhesive tape has been used to reduce this loss. There are no reports comparing the use of the commercial adhesive tape with the use of the modified silane-coated technique. The objective of this study was to compare section loss in slides using commercial adhesive tape, silane-coated microslides with the conventional technique or with the modified technique. Material and method: The TMA was constructed with hepatic tissue blocks embedded in paraffin, using a fixed base device, placing 32 cylinders of 2 mm in diameter in duplicate and 2.2 mm apart from each other. Fifteen 4-μm sections were placed on conventional silane-coated microslides at 4% (Group 1), 15 on silane-coated microslides with a modified technique (6% of silane and minimum use of acetone) (Group 2), and 15 on slides using commercial adhesive tape, according to the manufacturer's recommendations (Group 3). All microslides were processed by immunohistochemistry for cytokeratin 18, with antigen retrieval accomplished by incubation with citrate buffer pH 6.0 with microwave enhancement. Samples loss was quantified and expressed as: total (≥ 80%), almost complete (75% to 79%) or partial (50% to 74%). Results: The loss of sections was similar in all three groups (4.9 vs. 3.1 vs. 8.1, respectively) (analysis of variance [ANOVA], p = 0.3654). One slide usingcommercial adhesive tape showed artifactual ungluing of all sections and another one showed loss of 20 sampleson one side of the slide. None of the silane-coated microslides showed such artifact. Conclusions: Silane-coated microslides show adequate results, require less technical training and reduce the cost of TMA procedure, whatjustifies their use in research...

Microwave technique in histopathology and its comparison with the conventional technique.

125 formalin fixed human tissues from different organs and 50 fresh animal tissues were taken. Each tissue piece was divided into two. Fresh animal tissues were fixed and processed in a domestic microwave oven and formalin fixed tissue were only processed in microwave oven. Simultaneous conventional processing was also carried out. Among the fresh tissues, 34 pieces were fixed in 10% formalin and 16 were stabilized in normal saline, with microwave irradiation. For histoprocessing graded ethanol (70% and absolute) for 150 tissues and graded isopropanol (70% and absolute) for 25 tissues were used for dehydration in microwave technique. Chloroform for 95 tissues, xylene for 15 tissues and isopropanol for 65 tissues were used as clearing agent in microwave technique. Liquid paraffin was impregnating agent in all 175 cases. The oven was operated at 50% power for 10 cases and 40% power for 165 cases. Recording of temperature could not be done. Regarding fixation with formalin 80% cases gave satisfactory result, while with normal saline, only 30% cases were satisfactory. Regarding dehydration with ethanol 80% were satisfactory and with isopropanol 60% were satisfactory. Regarding clearing--both chloroform and isopropyl alcohol gave satisfactory results in 80% cases but with, xylene tissues were fragmented and brittle.

Disposable polyethylene wiremesh capsules for histopathological tissue processing.

An attempt was made to find a suitable alternative material for tissue carriers other than gauze and stainless steel capsules. Since polyethylene (high density) wire mesh is resistant to all acids, alkalis and inorganic chemicals and has no known solvent at room temperature, it is a suitable alternative disposable material for histopathological tissue processing purposes.