Analysis of gender-related publications. (A) Literature was classified into five research categories: Epidemiology, Pathophysiology, Clinical research, Management, and Outcomes. Research categories within the nine disciplines studied are illustrated. Equal distribution of research efforts would lead to a similar number of publications within each category. However, the categories of Pathophysiology and Epidemiology appear to be the most intensively investigated areas in most specialties. (B) The percentage of studies conducted on humans or animals was investigated. As all animal studies have been classified as "Pathophysiology" research, the relative percentages of animal model use can be derived by the ratio between the "Pathophysiology" data and the "Animal Study" data. Animal models are frequently used for basic research about sex differences; however, significant differences can be observed between specialties.