Dissections are an important component of the zoology lab class I teach, as we dissect a number of invertebrates and a rat. Dissection labs I've seen tend to be rather cookbook, with a single student, or group of students, getting an animal and then slowly working their way through it with instructor assistance.
Since each student is often asking the same questions as their classmates, I've been trying to help our lab students use their peers as resources. One technique I've used to encourage inter-group participation in the rat dissection lab is to have each group become an "expert group" that focuses on one specific area of the rat. I prop a large card on each table identifying that group's assigned area, and my student assistants and I go around the room early in lab helping all the expert groups become experts. Near the end of the period each expert group comes up to the front of the room and, using a video camera hooked up to a projector, gives a presentation about their section of the rat.
The expert groups have worked reasonably well; some students in each section consistently tour the room and ask the expert groups appropriate questions. However, students use their "expert" peers as a resource far less during the lab than they use me or my student assistants, and many students never ask another group a single question. The presentations at the end help open everyone up a bit, but by the time the presentations roll around most of the big questions have already been answered. I haven't tried doing the presentations soon after starting the dissection; that might make them more fruitful. Other problems with the presentations are that many structures are very hard to see with our video setup due to the low contrast, and the students aren't always the best presenters (though most do a great job).
One of my student assistants this semester came up with a neat idea to replace the presentations. She suggested providing each expert group with a set of labels (attached to pins) containing all the anatomical terms each expert group is responsible for. Groups would pin these labels to their dissected animals as soon as they found each structure, and after each group completed this task every major item would have a pinned label somewhere in the lab. The pins would provide an immediate, concrete check for the students to see if their ideas are correct (e.g. I could easily see if the rectum was labeled as the uterus), and the labels would provide other students an easy method of finding the location of new structures, motivating students to work with their peers. Once the labeling is complete students could go through the different lab tables to get an idea of where each structure is, and then go back to their rat to continue working, revisiting labeled rats whenever they needed to. The pinning could even be a graded assignment, with each group required to present their pinned animal to the instructor at the end of lab to check their work.