Microbiology is the study of microscopic organisms. They may be unicellular, multicellular or acellular. Pathology is the branch of medical sciences that deals with the examination of organs, tissues, and body fluids for the diagnosis of disease. Pathology describes the scientific study of disease which can be described as any abnormailty that is causing changes in the structure or function of body parts. In pathology, the causes, mechanisms and extent of disease may be examined.