Thomas McConnell is a physician specializing in pathology. He received his MD from the University of Texas Southwestern Medical School in 1962. In 1962-1963 he served as an intern at the University of Mississippi Medical Center and from 1963-1965 was a Medical Officer in the US Army. From 1965-1969 he served as pathology resident at UT Southwestern. From 1969-1977 he served as a pathologist at several hospitals. From 1977-1991 he was the owner and CEO of AM Laboratories, which provided medical laboratory services to physicians. clinics, insurance companies and hospitals. After selling his business in 1991 he served on several corporate boards and pursued business interests until in 1997 he was invited to join the pathology faculty at UT Southwestern Medical Center as Clinical Professor and to create and teach a pathology course in the Allied Health Sciences School, which he continues to teach. During his tenure in the pathology department Pathology he wrote "The Nature of Disease," a highly successful pathology textbook published by Lippincott in 2007.