Fig 5. Transverse MDCT section from a 4-month-old fetal specimen. The middle otic layer is seen as a smooth hypoattenuation surrounding the cochlea, circumscribed by the attenuated inner and outer layers. The dehiscence of the outer layer of the otic capsule (arrows) allows broad communication between the middle layer and the petro-occipital fissure. The petrous apex is not yet developed.