Buffered formalin

For light microscopic examination, liver tissue was fixed in 10 % buffered formalin, embedded in paraffin, sectioned and stained with hematoxylin and eosin. In some cases, preparations were stained with PTAH (phosphotungstic acid-haematoxylin), by the Van Gieson method and the PAS (periodic acid-Schiff)... 

The fixative system generally used is a two-vial technique with one vial containing 5 to 10% buffered Formalin and the other vial containing polyvinyl alcohol (PVA) fixative. A portion of the specimen is added to the fixative in a ratio of approximately 3 parts fixative to 1 part specimen and thoroughly mixed to ensure adequate fixation. An alternative to Formalin is Merthiolate-iodine-formaldehyde (MIF), which fixes and stains at the same time. If unfixed specimens are processed in the laboratory, fecal films may be prepared and immediately fixed in Schaudinn fixative. 

Fix a portion in 10% buffered Formalin and either fix a portion in PVA fixative or prepare three Schaudinn-fixed fecal films. Fix a portion in 10% buffered Formalin. 

Schistosomiasis Centrifuge entire midday urine. Add an equal volume of 10% buffered Formalin to the sediment. 

Sputum, for Nematode larvae or Paragonimus eggs Break up mechanically or digest 1 part sputum plus 5 parts 3% NaOH for 1 h. Centrifuge, and preserve the sediment in an equal volume of 10% buffered Formalin. 

Compound (Miles Laboratories, Elkhart, IN), snap-frozen, and cut into sections for comparison with paraffin-embedded cell sections (3) FFPE Cell Blocks Six cell pellets were fixed in 10% neutral buffered formalin immediately after harvest, at room temperature for 6,12,24h, 3,7, and 30 days, respectively. For further comparison with the cell model system, recently collected sample of human breast cancer tissues were processed by OCT-embedding and snap-freezing the corresponding routine FFPE block that was obtained from the Norris Cancer Hospital and Research Institute at the University of Southern California Keck School of Medicine (USC). This tissue block was processed routinely (formalin-fixed 24h and processed by automatic equipment). 

Figure 12.1 Typical good quality specimen. Small intestine fixed for 24 h in neutral buffered formalin after grossing at 2 mm. Most nuclei show good chromatin patterns, but cell membranes are indistinct. 

Figure 15.3 (a) Heat absorption in solutions of native RNase A (trace 1) and RNase A kept in 10% buffered formalin for 2 days (trace 2) and 6 days (trace 3) at pH 7.4 and 23°C. All samples were dialyzed against 75 mM potassium phosphate buffer (pH 7.4) prior to DSC. (b) Dependence of Td of the dialyzed RNase A samples on time of incubation in 10% buffered formalin at pH 7.4 and 23°C. (c) Heat absorption of solutions of formalin-treated RNase A fractions isolated by size-exclusion gel chromatography monomer (trace 1), dimmer (trace 2), and a mixture of oligomers with >5 cross-linked proteins (trace 3). Protein concentrations were 0.5 mg/mL. The thermal denaturation transition temperature (Td) is defined as the temperature of the maximum in the excess heat absorption trace associated with the protein s endothermic denaturation transition. See Rait et al.10 for details. 

The effect of heating on the structure of formalin-treated RNase A is shown in Figure 15.7a (far-UV region) and 15.7b (near-UV region). In both Figures 15.7a,b, trace 1 is the spectrum of RNase A (6.5 mg/mL) kept in 10% buffered formalin (pH 7.4) for 9 days and then analyzed at 23°C following removal of excess formaldehyde by fast dialysis. Trace 2 is the same sample after heated to 95°C at a rate of 5°C/min and allowing 10 min for temperature equilibration. 

The successful of recovery of RNase A functional activity by a heat-induced AR method suggested the possibility of recovering RNase A immunoreactivity as well. The immunoreactivity of native RNase A and RNase A that was incubated at a concentration of 4 mg/mL in 10% neutral buffered formalin for 1 day and then freed of formaldehyde by dialysis against PBS was compared using capture enzyme-linked immunosorbent assay (ELISA). Selected fractions that... 

Figure 15.10 SDS-PAGE of native RNase A (lane 1) and RNase A incubated in 10% neutral buffered formalin for 9 days (lane 2) or in 5% neutral buffered formalin for 1 day (lane 4). The formalin-treated samples were then demodified for4h inTAE buffer (pH 4) at 65°C 10% formalin oligomers (lane 3) and 5% formalin oligomers (lane 5). M, molecular mass markers in kDa. See Rait et al.11 for details.

The medium is removed and the colonies are fixed and stained, using 5% Giemsa in buffered formalin. Once the colonies are stained, the Giemsa is removed and the colonies are counted. 

Tissue processing tissue specimen (0.5 1.0 mm3) are fixed in 4% buffered formalin for 30 60 min, post-fixed in 1% osmium tetroxide in cacodylate or phosphate buffer, pH 7.2 7.4, stained en bloc for 30 min with 2% aqueous uranyl acetate, then dehydrated in ethanol and embedded in epoxy or acrylic resin. 

Fixation Fix tissue in 10% neutral buffered formalin (or equivalent) by placing slides in a shde rack and incubating them in a staining dish containing the fixative. Upon removal from formahn solution, rinse with tap and double distilled water (ddH20) to remove salts. 

Decant the PBS and carefully add 4 mL of 10% neutral buffered formalin down the side of the tube, overlaying the peUet without causing turbulence (see Note 10). Incubate overnight at 4°C. 

Neutral buffered formalin add 100 mL of 37 0% formalin to 900 mL deionized water, then add 4 g monobasic sodium phosphate and 6.5 g dibasic sodium phosphate. Bonin s fluid Combine 1500 mL picric acid (saturated in deionized water at 21 g/L), 500 mL formalin, and 100 mL glacial acetic acid. 

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