Comparative Morphometric Study of the Osseous Labyrinth in Humans and Animal Models Using Centerline Analysis

This study aimed to construct three-dimensional (3D) inner ear models in common animal models using micro-computed tomography (micro-CT) and a highly semi-automatic centerline-based method and to preliminarily assess the morphological similarities of their bony labyrinths to those in humans.

Temporal bones from three adult mice, three guinea pigs, three minipigs, and one human were scanned using micro-CT. After segmentation, 3D inner ear models were reconstructed. A highly semi-automated centerline method was established to estimate 3D properties and calculate length, volume, and angular parameters across species.

Detailed 3D models of the cochlea, vestibule, and semicircular canals were successfully constructed. The mean lengths and volumes of the inner ear and semicircular canals generally increased with body size, with the cochlear volume and length of minipigs demonstrating proximity to human data. Notably, numerical assessments have shown that the semicircular canals in both mice and minipigs closely resemble human structures.

Highly semi-automatic centerline-based measurements are effective tools for assessing 3D inner ear morphology. The bony labyrinths of minipigs demonstrated proximity to human inner ear parameters in terms of length, volume, and semicircular canal angles. However, mice exhibited an even closer resemblance to humans, specifically in semicircular canal angles. These findings provide preliminary guidance for the selection of animal models for various otological research fields.