The second edition of Comparative Anatomy and Histology is aimed at the new rodent investigator as well as medical and veterinary pathologists who need to expand their knowledge base into comparative anatomy and histology. It guides the reader through normal mouse and rat anatomy and histology using direct comparison to the human. The side by side comparison of mouse, rat, and human tissues highlight the unique biology of the rodents, which has great impact on the validation of rodent models of human disease.