title: "APUD" cells: fact and fiction.
abstract: Pearse's "APUD" cell theory helps define the ontogeny and differentiation programs of small polypeptide hormone-secreting cells of diverse tissue origins. Cells with such features may arise through one of multiple related pathways of epithelial cell differentiation ongoing in tissues of all embryonic lineages.
authors.affiliation: Oncology Center and Department of Medicine, The Johns Hopkins University Medical Institutions, Baltimore, MD 21231, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Baylin