Regarding embryology and developmental bio; Does anybody know the generic name applied to the class of chemicals that are secreted, and diffuse down their graident to induce changes in neighboring cells of the developing embryo? I'm leafing through Barrons bio and they don't mention the name. This is driving me crazy. When I took Dev. Bio a couple years ago it was mentioned no less than 12 times per lecture and now I can't recall it. Thanks for reading.