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The original Davidson® dyes are formulated to adhere to a side or edge of a specimen for orienting purposes. They were originally developed to be used with MOHS technique of orienting tissue. They are thicker in viscosity and have a high adherence quality for this purpose.
The Davidson® Small Specimen dyes have been formulated to easily “drop” onto a very small specimen in order to color the entire specimen. This makes it more visible in a cassette, thus less likely to be lost. This also makes it possible to process multiple small specimens in one cassette. The Small Specimen dyes have a thinner viscosity for easy “dropping”, but still adhere very well to the tissue through processing.
The Small Specimen dyes will not work for orienting tissue and the original dyes will not “drop” easily enough to color an entire small specimen.
There is no best color. Over the years, we’ve heard from customers citing each of our 8 colors as favorites. This is certainly due in part to personal preference and may also be attributed to differences in an individual lab’s histochemical processing techniques. The best color for you is the one that adheres best in your lab and which you find most easily distinguishable.
There is no consistent answer to this. Some colors stick better in one lab and other colors better in another lab. While on paper, all histochemical processing is similar, there are some differences from one lab to the next.
The best method is to receive the tissue fresh, blot free any excess fluids and then apply the dye. ALWAYS shake before use, as all colors have settling tendencies and will not perform as well without prior mixing. Using an applicator, apply a small amount of dye to the tissue margin. The key is to let the dye slowly bond with the tissue for 1-2 minutes. The emphasis is not on “drying” but on allowing the dye to “bond” with the tissue. Oxidative and reductive chemicals do not improve the bonding nor does blow drying or assisted drying. The excess dye is then blotted away and the tissue processed.
The above method is appropriate for formalin preserved tissue as well. The process is identical. The dye adherence is excellent, but is not quite equal to that obtained with fresh tissue.
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Margins: The dyes used in the classic fashion for margins are applied to the perimeter of the surgical specimen before it is cut or sectioned or otherwise altered. The dye adheres to the periphery and once the sectioning is complete, any place where dye is located is a tissue margin.
Many tumor margins today are not examined in the perpendicular fashion, but in the tangential fashion as originally described by Frederick Mohs. In these applications, anything on the slides represents tumor at the margin.
Orientation: The dyes are applied in such a way that they maintain tissue orientation. The typical orientations are superior, inferior, medial, lateral, right, left, etc. While there are numerous paradigms for the application of orientation markers, the most conventional is to section the tissue and then apply the marking dyes.
Under absolutely no circumstances can these dyes ever be applied to the patient. The dyes have been designed to adhere for life and any dye placed in the patient will remain for life. In addition, some of the dyes have been mixed with potentially poisonous chemicals. Furthermore, the dyes are not manufactured under sterile conditions.
We recommend minimal rehydration using distilled water. Be careful not to over dilute, as once the product has been diluted, we cannot guarantee it’s performance quality.
Extreme temperatures may affect the adherence quality of the dyes. Comfortable room temperature is the best climate for storage.
The dyes have a long shelf life, provided the caps are kept on tightly. If the caps are left off during lab procedures, the dyes may thicken due to evaporation. Please view our Return Expiration Statement.
The longer the dye is given to naturally “bond” to the tissue, the stronger the adherence quality. We recommend thinking of this as “bonding” time rather than “drying time. We recommend 1-2 minutes for “bonding”. Some have suggested a blow dryer may help speed up the process. This helps “drying” time, but it does not necessarily help “bonding” time. Some have suggested the use of fixative. If a fixative must be used for a particular process, we recommend simple acetic acid. A fixative may be appropriate when working with fatty tissues.
The Davidson® dyes can definitely be used successfully on both fresh and frozen specimens. Over the years, many labs have reported the use of the Davidson® dyes for many marking applications, and other processing. If you have a need for an orienting-type marking dye and cannot find information regarding the use of marking dyes and your particular test, we encourage you to test it yourself and see if it might work for your purpose. As always, we would appreciate hearing about your success so that information can be given to others who inquire.