Modified animal tissues, organs, and organ systems for use in simulated surgical procedures are disclosed. The tissues, organs, and/or organ systems can be modified by enhancing their electrical conductivity, by including simulated contents mimicking what would normally be present in live animals, and by having fake blood perfusing through them. Portions of different tissues, organs, or organ systems, which can be from the same or different animals, can be adhered to provide hybrid/chimeric tissues, organs, or organ systems, and also used for simulated surgical procedures. These modifications can provide surgeons with a more realistic experience during a simulated surgical procedure.