Functional tissue units in the Human Reference Atlas

Functional tissue units form the basic building blocks of organs and are important for understanding and modeling the healthy physiological function of the organ and changes that occur during disease states. In this comprehensive catalog of 22 anatomically based, nested functional tissue units from 10 healthy human organs, we document the definition, physical dimensions, blood vasculature connections, and cellular composition. All anatomy terms are mapped to the multi-species Uber-anatomy Ontology (Uberon) and cells are mapped to Cell Ontology to support computational access via standardized metadata. The catalog includes datasets, illustrations, and a large printable poster illustrating how the blood vasculature connects the 22 functional tissue units in 10 organs. All data and code are freely available. The work is part of an ongoing international effort to construct a Human Reference Atlas of the 37 trillion cells that make up the healthy human body.