TY - JOUR T1 - 3D Axonal Morphometry of White Matter JF - bioRxiv DO - 10.1101/239228 SP - 239228 AU - Ali Abdollahzadeh AU - Ilya Belevich AU - Eija Jokitalo AU - Jussi Tohka AU - Alejandra Sierra Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/12/24/239228.abstract N2 - Axonal structure underlies white matter functionality and plays a major role in brain connectivity. The current literature on axonal structure is based on the analysis of two-dimensional (2D) cross-sections, which, as we demonstrate, is precarious. We developed a novel pipeline for automated three-dimensional (3D) segmentation and morphometric analysis (ACSON) of the white matter ultrastructure. The automated pipeline eliminates the need for time-consuming manual segmentation of 3D datasets. We applied the pipeline to serial block-face scanning electron microscopy (SBEM) images of the corpus callosum of sham-operated and traumatic brain injury rats (n=1/condition) 5 months after injury. The 3D morphometry showed a substantial variation in axonal diameter along individual axons and the axonal cross-sections were elliptic rather than circular. The axonal diameter was significantly greater in the traumatic brain injured rat, indicating ongoing axonal alterations even at this chronic time-point. ER -