FIGURE 1.

Classical view of the cartilaginous sphenoid in human fetuses. Original drawings. Left‐hand side, an early stage (an early fetus); right‐hand side, a later‐stage (a midterm fetus). In the early stage, the cartilaginous sphenoid is composed of four parts: the basisphenoid (BS) (red part), orbitosphenoid (OS) (yellow part), alar process (blue part), and ala temporalis (blue part). The OS does not surround the optic nerve completely. The anterior end of the BS is similar to the adult morphology (arrow). In the later‐stage, the entire anterior margin of the OS (arrowheads) fuses with the ethmoid. The dorsum sellae (dorsum) is established. NC, notochord