Computed tomography in the study of the development of the skull base: 1. Normal morphology.

We examined 11 human fetuses (18 to 30 weeks' gestation) with high resolution CT to study the developmental ossification of the two main component structures of the skull base, the temporal and sphenoid bones. Computed tomography, with its excellent contrast discrimination, allowed clear visualization of the morphology of ossifying centers. Skull base growth during this gestational period was found to be a dynamic event with rapid changes in morphology and interosseous relationships. The growth of the sphenoid body on CT corroborates the studies done by Kodama, who used dehydrated skulls. The temporal bone proceeded in a stepwise fashion; complete encapsulation of the membranous labyrinth occurred before it grew anteroposteriorly to form the apex and mastoid.