Comparative Pathology

Sample Submission

Samples can be submitted in fixative, fresh (on ice), or frozen. Contact the lab prior to sample submission, and provide a completed Comparative Pathology Request Form with your samples. Please submit electronically via iLab, which requires a one-time registration. Once registered, the system will enable the submitter to place service requests, provide required approvals, and monitor progress.

Submission of fresh or frozen tissues
Drop off in the lab between 8:30 a.m. and 5 p.m.

Submission of fixed tissues
Drop off in the lab between 8:30 a.m. and 5 p.m.

Turn-around time

• Projects will be completed in the order they were received.
• For the technical portions of the projects (routine histology and established IHC protocols) the turn-around time is 1-2 weeks.

Pick-up of produced materials

• Produced slides, paraffin blocks or other materials will be in the CPSR lab for pick up after notification of project completion.
• Due to limited freezer space in our facility, frozen tissues must be picked up 4 weeks after project completion date.

Sample Collection

Fixative

• 10% neutral buffered formalin is the most commonly used fixative
• To assure good sample quality, collect samples as soon as possible after the death of the animal
• For thorough fixation, tissue to formalin ratio should be 1:10
• Transfer samples into 70% ethanol after complete fixation in formalin (usually overnight up to 24h for mouse tissues) if IHC procedure will be applied to the formalin fixed tissues.

Containers

• Please use wide mouth containers for fixed specimens. Tissues become rigid in fixative and can not be removed from the containers with narrow necks.

Whole mouse submissions

• If submitting the entire mouse, open thoracic and abdominal cavities to expose internal organs to fixative
• Ensure that there is adequate amount of fixative and the container has a wide mouth.

Histology

• Tissue-Tek VIP tissue processor and Tissue-Tek TEC embedding station
• 3 microtomes for cutting paraffin-embedded specimens
• Leica RM2125
• Microm HM315
• Olympus 4060E
• Leica polycut E heavy duty microtome
• Cryostat for cutting frozen sections
• Leica CM3050
• Leica Automated Cassette Labeler

Immunohistochemistry

• Dako DC3400 automated immunostainer

Pathology

• Nikon Eclipse E-800M bright field/fluorescence/dark field microscope equipped with a Nikon DXM1200 high resolution digital camera.
• Nikon Coolpix® 995 and Nikon Coolpix® 5700 digital cameras for gross and subgross (dissecting microscope) images
• Nikon Eclipse E-600W bright field microscope with SPOT Insight color digital camera
• Olympus BX-40F bright field microscope with SPOT Insight color digital camera
• Nikon SMZ1000 dissecting microscope

What is comparative pathology?

Pathology is the study and diagnosis of disease through examination of organs, tissues, body fluids, and whole bodies. Comparative pathology involves the comparison of diseases in animals as they relate to those in humans, with the goal of better understanding human disease. Although many human diseases occur naturally in animals, disease in animals also may be induced to mimic human disease.

What role does comparative pathology play in cancer research?

Cancer occurs naturally in animals, with different types of cancers occurring more often in certain species, strains, or breeds of animals. There are many advantages to studying cancer in animals, including the ability to induce the development of tumors in animals. Mice are the most commonly studied species and offer a particular advantage in that tumors may be induced through genetic manipulations.

The developmental biology of tumors, as well as methods to treat them, may be studied in animals much more easily than in humans. Even with the very sophisticated imaging techniques that are currently available, examination of the tissues by a pathologist is the "gold standard" for the diagnosis of cancer in animals.

What services does the Comparative Pathology Shared Resource provide for researchers?

We are a full-service pathology laboratory in that we offer support from the initial stages of the experiment (study design and preparation of research grant) through to the final stages (assisting with manuscript preparation after the results have been analyzed). We offer technical support for tissue collection, processing, and preparation of histological sections, and we also offer pathology support for interpretation and imaging of the tissues.

Investigators may use our resource for all of these activities or for only one of them (e.g., preparation of histological sections from a tissue block that has been embedded in paraffin), depending on the resources in their own laboratories.

Watch a video about the Comparative Pathology Shared Resource and its services.

What is an example of a typical research project for which you provide services?

An example of a typical project might be one where an investigator has used an experimental treatment to reduce the number and size of tumors in the lungs of mice. Our services may be used to provide descriptive information, such as determination of the type of tumors and whether they are malignant or benign, as well as quantitative information regarding the number and size of the tumors.

What kinds of expertise and educational backgrounds do the people who work in the facility have?

Our technical staff members have bachelor's degrees and/or have completed a 2-year histotechnology training course and all have considerable experience in a histology laboratory. Our veterinary pathologists have completed college, a veterinary medical degree, and residency training in veterinary anatomic pathology.

Currently, all of our pathologists have Ph.D. degrees and are board-certified in veterinary anatomic pathology. Most have been principal investigators on NIH grants and have an excellent understanding of the challenges that are faced by investigators.

How do you work with researchers as they prepare studies for publication in scientific journals?

Ideally, we first meet face-to-face with the researcher to determine his/her goals for the publication. We then take responsibility for writing up the methods and results for the pathology portion of the manuscript and also provide publication-quality images and figure legends. If the manuscript reviewers have questions regarding the pathology section of the manuscript, we assist in addressing those concerns.

What types of tissue samples do you typically work with?

Although we work with a wide variety of tissues from a variety of animal species, most commonly we work with soft tissues (vs. bone and cartilage) such as lung, liver, heart, and kidney from mice. These usually are fixed in formalin and embedded in paraffin for sectioning. We also work with samples of frozen tissue.

How and in what form are tissue samples sent to you?

For some studies we assist with tissue sampling and evaluation at the time of necropsy; however, most investigators send fixed tissues to our laboratory in formalin. Some investigators process their own tissues into blocks and send the blocks to our laboratory for sectioning. Learn more about sample submission.

What are the necessary steps in a typical project?

1. First, the investigator should contact one of our pathologists as early in the project as possible, ideally when studies are being planned and grants are being submitted, to explain the goals of the project and to ensure that the study design is appropriate and that there is a plan to correctly collect, fix, and process the appropriate tissues.
2. When tissues from the project become available, the investigator fills out a request form (Excel document) to submit electronically to our laboratory. This form contains information regarding the number and type of tissues that will be submitted, the type of technical work that is requested (e.g., routine H&E stains, immunohistochemistry preparations, special stains, etc.), and whether or not pathology interpretation is needed.
3. Then the tissues are submitted to our laboratory, either by being delivered by someone from the investigator's laboratory or by being left at our drop off site in room 580 of the Masonic Cancer Research Building.
4. The technical work generally is completed in 2-3 weeks, depending on the size of the project.
5. The pathology assessments occur after the technical work has been completed and the time required for these also varies depending on the size of the project.

How do you help researchers analyze the samples you prepare?

Depending on the goals of the project, our pathologists examine the tissue sections under a microscope and describe the changes that are present. Examples would include determination of whether or not there is tumor tissue present, the type of tumor and its features, and whether the tumor cells are extending into sites other than the primary site.

For definitive diagnosis of some tumor types or to detect specific molecular markers that are characteristic of particular cellular events such as proliferation or cell death, immunostaining of the tissues is required. This involves incubating the tissue section with an antibody that is directed against a specific tissue antigen. Visualizing an antibody-antigen interaction can be accomplished in a number of ways. One way is to conjugate the antibody to an enzyme that can catalyze a color-producing reaction.

How do communicate with researchers about results?

Although we are happy to meet in person with investigators or talk with them by phone, the majority of our communications are done electronically. When technical work is completed, the investigator is notified by e-mail and the blocks/sections are delivered to the Masonic Cancer Center drop off site. When pathology evaluations are completed, the investigator would be contacted by the responsible pathologist. Data tables, images, slide descriptions, etc., are shared electronically.

Is your work published often in journals?

We encourage investigators to include pathologists as co-authors on manuscripts. This ensures that the highest quality work is published, provides appropriate credit to the pathologist on the project, and ensures that reviewer critiques will be addressed by a person with the appropriate background and knowledge.

Why is it important for researchers to take advantage of the services the Comparative Pathology Shared Resource provides?

We strongly believe that we can add value to any project that includes pathology assessments. Our staff members have the experience to provide advice on study design, produce high-quality tissue preparations, and provide accurate pathological interpretations and expert manuscript assistance to investigators who are using laboratory animals in their research projects.