Together, the epithelial enamel organ and ectomesenchymal dental papilla and follicle form the tooth germ. Renal papillary necrosis is a form of nephropathy involving the necrosis of the renal papilla. The ampulla is specifically located at the major duodenal papilla. Dentin is derived from the dental papilla of the tooth germ. In inflammations the interdental papilla loses its concavity. The junction between the embryological foregut and midgut lies just below the major duodenal papilla. The lacrimal canaliculi open into the papilla. Odontoblasts, the dentin-forming cells, differentiate from cells of the dental papilla. There is a facial side interdental papilla and a lingual side interdental papilla. It seems to grow from below the free gingival margin/interdental papilla. Specifically BMP4 is found in the dermal papilla. Mesenchymal cells within the dental papilla are responsible for formation of tooth pulp. The ectomesenchyme cells condenses further and becomes dental papilla. Odontoblasts were originally the outer cells of the dental papilla. The minor papilla drains the duct of Santorini, superior in position to the major papilla.