title: The concept of the three R's. An introduction.
abstract: The development of the concept of the three R's--Replacement, Reduction and Refinement--is outlined. The concept has changed slightly since the early days and is now known as "alternatives to laboratory animals". Several examples of replacement, reduction and refinement systems are given with special emphasis on biological standardization. Suggestions for action by national and international bodies are included in the conclusion.
mesh_terms: D000818:Animals; D000830:Animals, Laboratory; D000831:Animals, Newborn; D007928:Lethal Dose 50; D012107:Research Design / Q000592:standards*; D013312:Stress, Physiological