title: Are morphogenetic tissue interactions mediated by transmissible signal substances or through cell contacts?
mesh_terms: D002448:Cell Adhesion; D002454:Cell Differentiation; D004627:Embryonic Induction; D007684:Kidney Tubules / Q000196:embryology*; D008648:Mesoderm; D012469:Salivary Glands / Q000196:embryology; D013116:Spinal Cord / Q000196:embryology