Fixation Conditions

Overfixation of specimens is also recognized by difficulty in sectioning because of excessive hardness of the tissue. This problem arises when tissues are fixed with formulations containing ethanol, methanol, or acetone. Excessive dehydration with an organic solvent may also cause tissue hardness, especially of small specimens (1-2 mm). Such 

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Eor printing on polyester, the fixation conditions are more rigorous than on other disperse dyeable fibers, owing to the slower diffusion of disperse dyes in polyester. Eor continuous fixation the prints are exposed at atmospheric pressure to superheated steam of 170—180°C for 6—8 min. A carrier may be added to the print paste for accelerated and fliU fixation. Dry-heat fixation conditions of 170—215°C for 1—8 min are less popular for printed fabrics, but are sometimes employed because of lack of other equipment. 

There are reactive softeners, some of which are N-methylol derivatives of long-chain fatty amides (10.241) while others are triazinyl compounds (10.242). The N-methylol compounds require baking with a latent acid catalyst to effect reaction, whereas dichloro-triazines require mildly alkaline fixation conditions. The N-methylol compounds are sometimes useful for combination with crease-resist, durable-press, soil-release and water-repellent finishes. In this context, the feasibility of using silane monomers such as methyltri-ethoxysilane (10.243), vinyltriethoxysilane (10.244), vinyl triace tylsilane (10.245) and epoxypropyltrimethoxysilane (10.246) in crosslinking reactions to give crease-resist properties and softness simultaneously has been investigated [492]. 

Table 12.19 Pad liquor formulations and fixation conditions for application of monofunctional and heterobifunctional reactive dyes by three continuous dyeing methods [162]...

Gong Y, Symmans WF, Krishnamurthy S, et al. Optimal fixation conditions for immunocytochemical analysis of estrogen receptor in cytologic specimens of breast carcinoma. Cancer (Cancer Cytopathol.) 2004 102 34-40. 

List of Fixation Conditions for Preparation of Plant Cells and Tissues for Transmission Electron Microscopy... 

The fixation conditions used to prepare cells for antibody application are assumed to preserve the distributions of the protein(s) being examined (2). Soluble proteins can be redistributed into inappropriate locations and... 

Proper fixation is one of the most critical steps in an in situ RT-PCR or in situ hybridization experiment, because each tissue type must have optimized fixation conditions. Particularly archival tissues may require individual specific treatment in order to meet with in situ experimental requirements. Errors in fixation will only be discovered after the entire hybridization process has been completed (see Note 10). 

Standard fixation conditions for disperse dyes on polyester fibers ... 

Plant plasma membranes and tonoplasts (vacuole membranes) are particularly sensitive to fixation conditions and fixation of the vacuoles can be quite problematic. If the fixation is inadequate, then the tono-... 

The fixation conditions used to prepare cells for antibody application are assumed to preserve the distributions of the protein(s) being examined (2). Soluble proteins can be redistributed into inappropriate locations and can be differentially extracted from native locations during the permeabilization and fixation of the cells before antibody application (3,4)- Further, no cell aggregation or alteration of the intracellular antigenicity should occur in the permeabilization/fixation treatment. The fixation/stain methodology, with and without permeabilization, can be accomplished in various ways depending on the exact site of the organelle or cell constituent to be stained. 

Hemmer and coworkers64 compared the influence of three different fixatives on immunoreactivity of P-gp antigen in tissue sections and reported that fixation conditions can strongly influence the staining results. Generally, Bouin s fixative was found to be inferior to Dietrich s or Lillie s fixative. Formalin was not considered in... 

This chapter summarizes our experience with this approach and describes some of the critical parameters involved in the preparation of rat neural tissue for LCM, with particular emphasis on protocols applied to the Arcturus Autopix LCM. This instrument has been superceded by more recent models, which are now marketed and distributed by MDS Analytical Technologies (http // www.moleculardevices.com). The principles described here, however, are applicable to tissue preparation for most LCM instruments. We describe two basic protocols for the isolation of samples of rat brain, first from unstained microdissected regions, and second, from brain cells that express specific antigens identified by immunostaining. In addition, we compare the effects of different fixation conditions on tissue recovery and RNA content using real-time QPCR. 

To determine optimum alcohol fixation conditions for the integrity and recovery of the RNA from the tissue, the extracts from each fixation were column-purified on RNA Arcturus Picopure RNA Isolation Kit , and residual DNA was degraded... 

A comparison of the relative content of the GAPDH template in the samples obtained from each fixation condition is shown in Fig. 4. The highest yield of GAPDH mRNA was obtained with 70% ethanol fixation. By comparison, 100% methanol fixation produced 40% less yield of GAPDH mRNA. The 100% ethanol and 70% methanol fixations yielded more GAPDG mRNA than from 100% methanol but less than with 70% ethanol. 

No attempt has been made in this chapter to measure wicking and to correlate it directly with microviscosities, because the kinetics of sorption may be complicated by difiusion of liquid into the fibers rather than capillary movement between fibers (13). In a real printing operation, the fixation conditions and rate of drying of the print, the type of fabric used and its thickness, the twist of the yams, and the type of fibers used have a strong influence on wicking behavior (11). 

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