A medical scientist studies the parenchyma of the kidney. What specific type of science is this?

Parenchyma is the functional tissue of an organ. The specific type of science that is the study of tissues is histology. Biology is the study of life in general, and histology, anatomy, and physiology are all different subdisciplines within biology. Anatomy is the study of the various structures of the body and their locations. Physiology is the study of how various parts of the body function.