Open Access
Review
Table 4
Advantages and disadvantages of selected mounting media about microscope slides and unpublished observations by various persons [52].
| Name | Advantages | Disadvantages |
|---|---|---|
| * Canada balsam | The medium is highly durable, with a lifespan exceeding 150 years. | Contains harmful components and must be handled under a hood. |
| Slides can be mounted using clove oil, or phenol as mounting agents. | Requires a full, time-consuming dehydration series. | |
| Ethanol dehydration and transfer via xylene or clove oil can make some taxa brittle; alternatives (e.g., isopropanol, n-butanol, Cellosolve™, 1,4-dioxane, Histoclear, terpineol) may reduce breakage. | ||
| Specimens may blacken if xylene is replaced with phenol or if residual potassium hydroxide remains. | ||
| High refractive indices can obscure unstained structures. | ||
| Complete drying can take years without hot-plate drying. | ||
| The medium yellows and darkens over time, especially when cleared with clove oil. | ||
| Some stains weaken, and cationic dyes may fade if the medium becomes acidic – which can occur spontaneously over time. | ||
| DMHF (dimethyl hydantoin formaldehyde) | High transparency | |
| Good refractive index | Possible yellowing over time | |
| Excellent visibility of structures | May alter some stains | |
| Fairly good stability of the preparations | Not suitable for formaldehyde-sensitive stains | |
| Compatible with many staining techniques | Air bubbles, slow drying time | |
| Good adhesion between slide and coverslip | Mounting medium sensitive to humidity | |
| Good protection of samples | Mounting is difficult to reverse | |
| Formaldehyde is toxic, irritant, carcinogenic | ||
| * Euparal (transparent) | Durable medium with a lifespan over 50 years. | Contains harmful components and must be handled under a hood. |
| Mounting directly from 80% ethanol is possible (manufacturer recommendation). | Ethanol dehydration and transfer via Euparal Essence can make some taxa brittle, but using isopropanol may reduce this issue. | |
| Does not mask unstained structures and does not yellow or become brittle over time. | ||
| Has a refractive index more suitable than Canada balsam for Diptera. | ||
| Works well for thicker specimens due to minimal shrinkage and bubble-free drying. | ||
| Remains soluble in 95% ethanol, allowing re-mounting even after many years. | ||
| Hoyer fluid | Specimens can be mounted alive or directly from water, ethanol, or formaldehyde. | Delicate plant specimens can collapse unless the medium is added gradually, which is time-consuming. |
| Maceration yields excellent cuticle quality. | Cavities and crystals may form in fewer than 10 years. | |
| Has a favorable refractive index and can be enhanced with iodine staining for higher contrast. | Maceration can become excessive depending on chloral hydrate concentration and exposure time. | |
| Acetic acid in the formula can expand arthropod appendages. | Components of the medium may separate, and fine granulation can appear within months or years. | |
| Some specimens may remain stable for 40–60 years. | Blackening of the media has been reported. | |
| Water-soluble, allowing easy re-mounting. | ||
| CMCP-9 (= carboxy methyl cellulose phenol) | Specimens can be mounted directly from media such as water, ethanol, glycerol, or formaldehyde-containing solutions, and their internal organs may be macerated when necessary to facilitate general examination or preparation. | This medium can develop crystals and darken over time, and it can sometimes macerate specimens more than intended. Unless the slide is carefully ringed, thicker samples will not do well in it because they can shrink and create gaps around the edges of the coverslip. It is not suitable for stained specimens or calcified materials, and its drying time is slower than CMC. |
| Eukitt™ | Durable medium lasting over 30 years. | Contains harmful components and must be handled under a hood. |
| Compatible with many solvents for mounting, including acetone, benzene, chloroform, dioxan, ether, isopropanol, methyl benzoate, terpineol, toluene, and xylene. | Requires a full, time-consuming dehydration series. | |
| Dries quickly and has a slightly acidic pH. | Not ideal for thicker specimens due to shrinkage and gas-bubble formation. | |
| Does not noticeably darken with age. | Coverslips may detach over time unless glass is cleaned well and sealed. | |
| Suitable for various stains (e.g., fuchsin, hematoxylin, methyl green, methyl violet, methylene blue). | May show incomplete polymerization around collagen fibers. | |
| Specimens can be re-mounted after years by soaking in xylene for an extended period. | ||
| Enecê | Highly durable medium, lasting at least 50 years. | Requires a full, time-consuming dehydration series. |
| Enecê does not darken over time. | Ethanol dehydration and transfer via clove oil can make some specimens brittle. | |
| It is more malleable, allowing for the dissection of insects in the medium, as well as providing a reasonable amount of time for positioning morphological structures. | The insect continues to be clarified although very slowly; this can make it difficult to see very small structures, such as sensilla, ascoids, and simple setae. | |
| Low cost. |
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