Practice question

Classic induction discovered by Spemann and Mangold involves dorsal involuting mesoderm signaling to overlying ectoderm to change its fate. Chordamesoderm secreting soluble antagonists Chordin, Noggin, and Follistatin antagonizes BMP signaling in dorsal ectoderm, preventing epidermal fate and allowing neural differentiation forming neural plate. Ventral ectoderm under active BMP remains epidermis. Ectoderm-mesoderm interaction is therefore required for neural plate formation, illustrating embryonic induction where one germ layer influences fate of another through secreted factors rather than autonomous differentiation program, demonstrating paracrine regulation of cell fate during vertebrate organogenesis and patterning.