Walsh & Hoyt: Chordomas

The notochord (also called the embryonal chorda dorsalis) is usually described as developing from a furrow-like thickening of the endoderm in the axial line beneath the neural groove; however, the exact roles of the endoderm, mesoderm, and ectoderm in the formation of the notochord are unclear. The notochord eventually forms a rod of cells that separates completely from the endoderm and lies between it and the neural tube. A more detailed discussion of the embryogenesis of the notochord and the skull base can be found in any general embryology text.