There’s no substitute for the hands-on experience students gain when dissecting preserved specimens. But the chemicals and cutting instruments involved require extra safety precautions. Keep reading for dissection safety tips that will help you prep your lab and your students to ensure everyone stays safe and the focus stays on learning.
Start by introducing basic tools and techniques
Before you introduce the specimens, go over all of the dissection instruments and their uses with your students. Instruments may include blunt probes, forceps, tweezers, teasing needles, T-pins, scissors, and scalpels. Pay special attention to scalpels and other cutting instruments, as they have the greatest potential for causing injury when used incorrectly.
Share the following tips:
- When dissecting, don’t cut down too hard — let the blade do the work. Cuts should be long and precise. Multiple short cuts, chopping, or hacking could damage the specimen.
- Scalpels need to be sharp so that cutting isn’t a struggle. Difficult cutting can lead to slips that can damage the specimen or hurt students. Tell students that if they’re struggling, they should switch to a different tool, such as scissors.
- There are two different types of grips students can use when cutting with a scalpel, both of which are demonstrated in the video below.
- Overhand grip: Used with a larger scalpel, such as a #22 blade, for cutting tough tissue like fascia.
- Pencil grip: Used for more precise incisions made with a smaller scalpel, such as a #10 blade.
- When passing any instrument to another person, present it with the handle extending out. For scalpels, make sure that the unsharpened flat edge of the blade is facing your hand.
- If you’re using a scalpel with a removable blade, take special care when replacing the blade. A safe technique for both removing and replacing a blade is demonstrated in the video below.
- For personal protective equipment, equip everyone with chemical-resistant safety glasses or goggles, gloves, and aprons. Ensure that your lab space is well-ventilated, and make sure that everyone knows proper eye-washing protocol and the location of the closest first-aid kit. During lab time, prohibit eating and drinking.
- Finally, always use a dissection pan or tray. Make sure students know never to dissect a specimen while they are holding it.
During dissection, pay attention to your students to make sure that everyone is comfortable. If you have students that aren’t comfortable dissecting specimens, you can still give them an inside look with specimen display sets and interactive models.
Select the safest specimens
The majority of preserved specimens available are fixed initially in formaldehyde. While it is still the best tissue fixative around, it is classified by the U.S. Environmental Protection Agency (EPA) as a probable human carcinogen.
To minimize your students’ exposure and your own exposure to formaldehyde, look for manufacturers that are transparent about their preservation process and provide a Safety Data Sheet (SDS).
Nasco Education developed a nontoxic, low-odor preservative solution over 50 years ago, and today it’s used to provide over 200 different preserved specimens to schools. Every specimen has been prepared with NASCOGuard® — a 99.7% formaldehyde-free fluid that exceeds OSHA standards.
Our skilled technicians remove the original formaldehyde fixative in a series of water baths, then perfuse the specimens with propylene glycol to inhibit the growth of decay organisms, ensure moist specimens, and lower the vapor pressure of any residual formaldehyde. Polypropylene glycol is not a toxin and has been approved for use by the U.S. Food and Drug Administration (FDA). You may be surprised at how commonly it’s used in items you eat or apply every day, including processed foods, cosmetics, and lotions.
If you want more details about why NASCOGuard preserved specimens are ideal for educational environments, watch the video below.
Another quality measure to consider when selecting specimens is color-coded injections. Key structures can be injected with colored latex to make it easier for students to identify and differentiate organs and structures, providing an enhanced learning experience. Nasco Education specimens are available with three levels of color-coding.
- Single injection: arteries shown in red
- Double injection: arteries shown in red, veins shown in blue
- Triple injection: arteries shown in red, veins shown in blue, and hepatic portal system shown in yellow
Practice safe specimen storage and disposal
Proper storage of specimens will not only keep your lab safe but also ensure that your specimens stay in top condition. For all specimens, the key is to keep them moist and avoid letting them dry out.
For dissections that take more than one class period, your short-term storage options are to either return specimens to their original container or use a dissection tray that comes with a plastic cover. If specimens do start to dry out, you can remoisten them with the residual fluid from the container.
For long-term storage, specimens should be kept in a tightly sealed container in a dry place at room temperature — no refrigeration or freezing is needed. Nasco Education specimens preserved with NASCOGuard will remain usable indefinitely when stored properly, so you can be confident of consistent results year after year.
You can choose to receive your specimens in a vacuum-sealed bag or a pail. Pails are a great choice for when you want to order a bulk amount of specimens but don’t need to use them all at once. All specimens in the pail should be submerged in the NASCOGuard fluid. If you need more fluid at any time, it’s available in both concentrated and ready-to-use forms.
Learn more about preserving Nasco Education specimens in the video below.
Once you’ve done your homework and checked everything off your dissection safety checklist, you and your students will be ready to enjoy one of the most memorable parts of a biology or anatomy class.