Recombination of the epithelium and mesenchyme between quail anterior submaxillary gland (elongating type) and quail anterior lingual or mouse submaxillary gland (branching type) was effected in vitro to clarify whether the elongating morphogenesis was directed by the epithelial or the mesenchymal component. Quail anterior submaxillary epithelium recombined with quail anterior lingual or mouse submaxillary mesenchyme came to branch. Conversely, quail anterior lingual or 12-day mouse submaxillary epithelium recombined with quail anterior submaxillary mesenchyme came to elongate, though the mesenchyme was less effective with 13-day mouse submaxillary epithelium. These results suggest that the elongating or branching morphogenesis of quail salivary glands is controlled by the mesenchyme.