What are preserved biological specimens?

Preserved biological specimens are plant or animal units that are treated with chemicals to prevent their decomposition so they can be examined and dissected over time. Preserved specimens are used by biology instructors at all levels of instruction to teach anatomy. Dissection of preserved specimens provides the student with a hands-on experience of learning an organism’s anatomy using the actual organism.

How are specimens fixed and preserved?

The fixation of all specimens involves chemically altering proteins so that bacteria and fungus cannot cause decomposition. This chemical alteration is accomplished by treating the specimen with a chemical fixative. These chemicals attach to the specimen’s tissue proteins causing them to crosslink to other proteins. This bonding and crosslinking changes the specimen tissues into decomposition resistant structures. The protein fixation can cause a color change and hardens the tissue.

Delta Biologicals primarily uses a diluted (3.7%) formaldehyde (formalin) fixative; however, due to concern over formaldehyde exposure, Delta Biologicals also offers a 100%-free formaldehyde fixation called Safe-Way. Safe-Way is the only 100% formaldehyde free fixation process available on the market. Our Safe-Way process involves a fixative that is consumed during the fixation process so that none of the chemicals remains in the specimen. Safe-Way specimens offer high-quality specimens that allow students and instructors with concerns over formaldehyde exposure the opportunity to perform worry-free dissections. After fixation of tissues, specimens are stored and packaged with our proprietary preservative, Delta-Sol.

What is Delta-Sol?

Delta-Sol is a non-toxic formaldehyde-free preservative and holding solution that inhibits decay, fungal and bacterial growth, and prevents desiccation of the specimen. After fixation, most Delta Biologicals specimens are washed and stored in this non-formaldehyde preservative fluid, Delta-Sol. Specimens are never shipped in formaldehyde and most are shipped in Delta-Sol. These washes, combined with odorless Delta-Sol, greatly reduce formaldehyde levels.

Packaging: what is the difference between Vac-Pac and Pail-Pac?

Delta Biologicals offers two types of packaging: Vac-Pac and Pail-Pac. Vac-Pac specimens are moist packed in a vacuum-sealed Mylar coated polyurethane bag. Pail-Pac specimens are packaged in liquid in a plastic pail or jar. Vac-Pac has lower shipping costs but is less convenient for long-term storage and reusability of specimens. Pail-Pac allows for convenient storage and re-using specimens on different days, but is more expensive to ship. For some specimens, Delta Biologicals has determined that a single packaging method is optimal and no packaging choices are available.

What are plain, single, double, and triple injected specimens?

Most preserved specimens are offered in a variety of color latex injections in different sections of a specimen’s circulatory system. This is so students easily find and identify features of the circulatory system. A plain specimen is a specimen without any color injections. All specimens are available as plain specimens. Most of the larger, more popular specimens are offered with color injections. A single injected specimen has its arterial system (the part of the circulatory system that leads away from the heart) injected with red-colored latex. A double injected specimen has had its venous system (the section of the circulatory system that allows the blood to return to the heart) filled with blue colored latex in addition to having the arterial system filled with red latex. Triple injected specimens, in addition to having their arteries and veins colored with red and blue, have the hepatic portal system (a part of the circulatory system that conveys nutrients absorbed through the small intestines to the liver) filled with yellow latex.

There are some exceptions to this, such as with sharks. Please refer to the specimen injection page for more information.

How should I care for my preserved specimens?

Preserved specimens do not require refrigeration of any kind. They should be kept away from freezing or very hot temperatures, and not left in direct sunlight. They should be left in the shipping containers until used. The two most important difficulties to watch for are drying and fungus or mold growth. Both of these concerns are solved by ordering specimens in pail pack as the fluid within the pails is specially formulated to both prevent drying and to inhibit mold growth. If you purchased specimens packed in vacuum-sealed plastic bags, the specimens should be kept in the bags until needed for use. After they are worked on for the day, students should keep them in specimen bags tightly sealed with a rubber band. Holding fluid sprays should be used both during dissection to prevent drying of the specimen and before the specimen is wrapped in its storage bag.

Delta Biologicals offers holding fluid spray, holding fluid concentrate, and storage bags.

Are Delta Biologicals’ specimens safe to have in my classroom?

Delta Biologicals is committed to providing you with premium products and specimens safe for dissection in the classroom environment. Some specimens may contain a small amount of residual fixative within the body cavity or as drainage within the polybag. We recommend this residual fixative be removed by rinsing with water or Delta-Sol. Rinsing the specimen’s body cavity under flowing water can be done in any sink as the wastewater can easily be handled by municipal wastewater treatment systems and there is no cause for concern.

Safety Data Sheets (SDS) are included with each order and should be referred to for specimen specific information.

How do I dispose of specimens?

Delta Biologicals’ preserved specimens are not considered hazardous waste and normally may be disposed of in the usual solid waste manner; however, as restrictions and regulations vary, we suggest contacting your local waste management department to determine appropriate disposal methods.

The excess holding fluid leftover from shipping and storage pails can usually be disposed of down any sewer drain. However, once again if there is concern regarding this inquire with the local wastewater authority.

Where can I find each product's SDS?

Each specimen’s SDS is included in its packaging. The SDS sheets can also be found on our website on the product’s page or on the resources page.

I lost my SDS, how can I find a new document?

If the specimen’s SDS sheet is lost, please visit our resources page. On the label of each specimen, in the lower righthand corner, is an SDS indicator code. This code can be used in conjunction with our SDS Resources webpage to identify the correct SDS that goes with the specific specimen.

How does Delta Biologicals charge for shipping?

Due to the nature of the industry, Delta Biologicals will not charge for shipping when orders are placed. Instead, Delta Biologicals will only charge the customer shipping once the product has shipped. This allows Delta Biologicals to remain flexible to the customer’s needs, such as a change in shipping data and methods or added/ subtracted products from the order at no cost.

Delta Biologicals pledges to find the lowest shipping cost option available that aligns with each customer’s specific needs.