Instructors Reconsider Dissection's Role In Biology Classes

HONING SKILLS: Trinity biologist Robert Blystone says dissection provides the opportunity for students to develop scientific observational skills. Poring over a frog's insides once was nearly synonymous with biology class. Although many life scientists contend that dissection is crucial to understanding body form and function, several factors have converged to challenge such use of animals in the classroom. "The dissection of anatomical specimens such as the fetal pig has fallen on hard times

Nov 10, 1997
Ricki Lewis

HONING SKILLS: Trinity biologist Robert Blystone says dissection provides the opportunity for students to develop scientific observational skills.
Poring over a frog's insides once was nearly synonymous with biology class. Although many life scientists contend that dissection is crucial to understanding body form and function, several factors have converged to challenge such use of animals in the classroom. "The dissection of anatomical specimens such as the fetal pig has fallen on hard times in the introductory college biology laboratory," observes Robert V. Blystone, a professor of biology at Trinity University in San Antonio, Texas.

At the high school level, objections to dissection largely reflect animal rights concerns. Five states (California, Florida, New York, Pennsylvania, and Rhode Island) have passed legislation guaranteeing students the right to refuse to dissect without penalty. On the college level, the issue is more complex. Although animal-rights activism certainly impacts the use of dissection, shifting curricular emphasis toward molecular biology, coupled with proliferation of technological alternatives to dissection, has prompted many instructors to reconsider the traditional dissection exercise.

The Reston, Va.-based National Association of Biology Teachers, which represents both high school and college educators, leaves the dissection decision up to instructors. However, the organization "acknowledges that no alternative can substitute for the actual experience of dissection or other use of animals and urges teachers to be aware of the limitations of alternatives," according to a statement from the board of directors. Several other professional scientific and educational societies have issued similar statements, including the Human Anatomy and Physiology Society and the American Society of Ichthyologists and Herpetologists. But students sometimes feel otherwise.

Karl Gossot, program assistant at the Ethical Science Education Coalition (ESEC) in Boston, fields several dozen calls a week from students, mostly from high schools, who wish to decline dissection without suffering academically. "A typical call is a student who says she has to dissect a mink or a cat in advanced-placement biology," he reports. "She doesn't want to do it, but the teacher says she has to or she shouldn't take the class. Although a lot of teachers are flexible, sympathetic, and willing to give alternatives, the burden is usually on the student to find the alternative."

ESEC consists of educators, students, and concerned others who champion the right to refuse to dissect. The organization provides detailed lists of alternatives, lends such products to teachers, maintains a hot line, and conducts workshops at national meetings to demonstrate use of alternatives. Stand- ins for animals include computer simulations, models made of synthetic materials, and, in the case of veterinary schools, allowing students to operate on sick animals to help them rather than experimenting with and hence killing healthy animals (see accompanying story).

'TOTALLY UNNECESSARY': UC-Davis's Nedim Buyukmihci contends that models of the human body are more informative than dissection.
Nedim C. Buyukmihci, a professor of ophthalmology at the University of California, Davis, School of Veterinary Medicine, opposes dissection, citing studies that demonstrate no difference in achievement between students who dissect and those who do not. "As one who did not dissect in high school, and who now is a veterinarian and trains doctors-to-be, I can unequivocally state that the experience of dissection is totally unnecessary for the biologically minded precollege student." He contends that models of the human body provide more accurate information about human anatomy than does dissecting nonhuman animals.

Dissection also is being pushed aside to make way for molecular material and for more inquiry-based experiments. "Currently molecular biology is in, and gross anatomy is out. Our current obsession with molecular biology has caused many to throw out the fetal pig with the amniotic water," says Blystone.

Jeffrey Carmichael, an assistant professor of biology and laboratory coordinator at the University of North Dakota in Grand Forks, has eliminated pig dissection to fit the changing curriculum in introductory biology. Although he maintains that dissections are valuable, "I decided to omit them this year primarily because they didn't fit well with what is covered in lecture. We used to spend three weeks dissecting the pigs in lab and the students had to learn [or] memorize a fair amount of detail, none of which pertained to lecture. Now, we do a few more experimental, activity- oriented labs."

Others agree that the descriptive nature of a dissection exercise does not quite fit a pedagogical philosophy or curriculum that stresses application of the scientific method. At Rensselaer Polytechnic Institute, biology professor George F. Edick has replaced dissection in the introductory lab course with a program in which students design and carry out experiments using a rapidly growing plant. Edick had grown frustrated trying to get students to approach dissection as an inquiry-based investigation. "I tried several ways to convince students that dissection was a very useful tool in biology. I asked them to replace organs back into the pig using incorrect spatial orientations and then ask such questions as, 'Okay, you have used the sequence mouth-small intestine-stomach-why would this be a problem in a live pig?' It didn't work. I still could not elevate, in the students' minds, dissection above something regarded as an easy and 'fun time' activity in lab," Edick says.

NO PLASTICINE: An important part of dissection, according to Illinois biologist Howard Buhse, is seeing natural anatomical variation.
Organizations Concerned With Dissection

American Association of Anatomists
9650 Rockville Pike
Bethesda, Md. 20814-3998
(301) 571-8314
Fax: (301) 571-0619

Ethical Science Education Coalition
167 Milk St., #423
Boston, Mass. 02109-4315
(617) 367-9143
Fax: (617) 523-7925

Institute of Laboratory Animal Resources
National Research Council
2101 Constitution Ave., N.W.
Washington, D.C. 20418
(202) 334-2590
Fax: (202) 334-1687

Dissection Alternative Products

A.D.A.M. Software Inc.
1600 RiverEdge Pkwy.,
Suite 800
Atlanta, Ga. 30328
(800) 755-2326
Fax: (770) 988-0611

Digital Frog International Inc.
Trillium Place
7363 Calfass Rd.
Puslinch, Ontario
Canada N0B 2J0
(519) 766-1097
Fax: (519) 767-9994

Engineering Animation Inc.
ISU Research Park
2321 North Loop Dr.
Ames, Iowa 50010
(515) 296-9908
Fax: (515) 296-7025

Despite the increasing availability of dissection alternatives, many instructors still heartily support dissection. "Students learn respect for the complicated aspects of how an animal is put together and learn from the variability in construction of these elements. Finally, they learn about themselves," contends Howard E. Buhse, associate director of the department of biological sciences at the University of Illinois at Chicago. Buhse uses already dissected human cadavers to teach anatomy to physical education majors and nurses, who would not otherwise view the insides of a human until later in their education. "It beats the hell out of those Plasticine models, where the liver looks like a perfect liver, and the kidneys are right where they should be," he adds. Many instructors have students measure the same organ in different specimens to note natural anatomical variation.

Part of the problem in getting the most from dissection exercises is to do them in appropriate courses. Robert M. Dawley, cochairman of the biology department at Ursinus College in Collegeville, Pa., reserves dissection-of cats-for anatomy classes and feels that anatomy does not belong in introductory biology. "Our elimination of anatomy from introductory biology has nothing to do with opposition to dissection, but rather is based on the pedagogical philosophy that introductory biology should minimize descriptive biology and concentrate on developing creative scientific thinking," he explains.

Some introductory course instructors feel that dissection is appropriate for biology majors, but not for nonmajors. For example, James Mahaffy, a professor of biology at Dordt College in Sioux Center, Iowa, uses the already-dissected pigs from zoology courses in the nonmajors' biology course. This is sufficient to show students where organs are located.

Dissection is perhaps most valuable for students heading for careers in the health sciences, allowing them to see if they've chosen the right field. Mindi Mitchell, a biology major at Purdue University, found her dissection experience worthwhile when she recently worked in the operating room at a nearby hospital. "My experiences with the fetal pig taught me much about anatomy. Most of the human anatomy was just like that of the pig, only larger. I was often quizzed by the surgeons, and many of them were surprised that a premedical student with only one semester of biology could answer their challenging inquiries."

INVALUABLE: Purdue professor, Mary Gray, believes that the dissection experience also can benefit nonmajors.
Mitchell's professor at Purdue, Mary H. Gray, believes that the dissection experience can benefit nonmajors, too. "It has direct relevance to the parts of the students' own bodies. It should also help them with medical terms, like bronchitis and gastritis," she says.

For those who opt to continue dissections in their courses, there are ways to make the experience both inquiry-based and fun, while also providing alternatives for those who object. An anatomical specimen is "seething with questions to be answered," says Blystone. "Does the cross-sectional diameter of the two primary bronchi add up to more than the diameter of the trachea? Does removal of a cat's tail change its center of gravity? Many students can hack their way into their specimen's stomach but have no idea how to measure the volume of that organ. Dissection provides the platform for thoughtful observations, and is not just a vehicle for naming the structure pierced by pin No. 16. Dissection, properly done, provides the opportunity for students to practice and develop the observational skills that all good scientists should have."

Performing surgery on animals is not the only way to study anatomy. Alternative approaches have pros and cons. "Students remember better if they actually peel back the skin rather than doing a virtual dissection. On the other hand, students who use an alternative don't have the feel, the smell, and the other senses of a real dissection-but they also don't have the emotional response," says Stephen Loomis, a professor of zoology at Connecticut College in New London.

Loomis uses CD-ROMs from A.D.A.M. Software Inc. in Atlanta in his sophomore-level anatomy and physiology classes. "The graphics give the user the ability to peel off layers, just like in a dissection," he says. A.D.A.M. also allows instructors to tailor lessons by importing precisely the graphics wanted. "People put their lessons on the [A.D.A.M.] Web site. A.D.A.M. is cheaper than a cadaver, and you don't have the same problems that you do when using a cadaver," Loomis notes. And although he wouldn't want to go to a surgeon who had never practiced on the real thing, he believes that for introductory biology courses, A.D.A.M. provides a good look at human anatomy for students who otherwise wouldn't get anything else.

The Dissectable Human, offered by Engineering Animation Inc. (EAI) of Ames, Iowa, is a CD-ROM that presents a three- dimensional atlas of the two-dimensional cross-sectional images of a male cadaver that constitutes the National Library of Medicine's Visible Human project. The Visible Human is Joseph Paul Jernigan, who was executed in 1993 at age 39 for committing murder. He donated his body to science- and ended up as 1,800 1-mm-thick magnetic resonance imaging and computerized tomography slices on the Internet ( He has since been joined by a Visible Woman (Notebook, The Scientist, Oct. 14, 1996, page 30). The Dissectable Human's tissues-a 3-D version of Jernigan-can be removed repeatedly, and tissues can be viewed microscopically and from different angles, says Carol Jacobson, senior director of business development at EAI. "Plus, you can't take a cadaver home; Dissectable Human is portable and can be viewed on a PC," she adds.

Millions of frogs are killed each year for use in biology classrooms. An alternative is the Digital Frog, a CD-ROM available from Digital Frog International Inc. of Ontario, Canada. The Digital Frog in some ways offers a more complete view of the animal than does a dissection by presenting ecology as well as anatomy. The user can hear frog mating calls and watch muscles move bones and blood circulate. Similar CD-ROMs simulate dissecting the bullfrog, cat, rat, crayfish, earthworm, fetal pig, and perch.

Ricki Lewis, a freelance science writer based in Scotia, N.Y., is the author of several biology textbooks. She can be reached online at